Some days you want Boston Cream Pie without turning on the oven. These no-bake bars deliver the same silky custard and shiny chocolate snap on a buttery cookie base. Think classic diner dessert—just faster, cooler, and party-friendly.

By the end of this recipe, you’ll know the exact ratios for a clean slice, how thick to cook the custard (with temps), and the best chocolate-to-cream balance for a ganache that sets but still bites softly.

Why This Recipe Works (The Tested Formula)

We lean on a sturdy biscuit crust + stovetop pastry-cream filling + 1:1 ganache. The winning ratio for clean bars:

• Crust: 200 g cookie crumbs (≈2 cups) : 85 g butter (6 tbsp).
• Custard: 500 ml whole milk (2 cups) + 4 yolks (≈70–80 g) + 30 g cornstarch (¼ cup) + 100 g sugar (½ cup) + 5 g powdered gelatin (1½ tsp bloomed in 45 ml/3 tbsp cold water) for sliceable stability.
• Ganache: 180 g chocolate : 180 ml cream (1:1 by weight/volume) for a soft set.

Most people undercook the custard. Cook to 82–85 °C / 180–185 °F, whisking 1 full minute after it starts to bubble so the cornstarch fully gelatinizes. For another easy, no-bake crowd-pleaser, try our Strawberry Banana Cheesecake Salad.

Ingredients You’ll Need (with Smart Substitutions)

You’re building three layers with pantry staples. Whole milk and yolks make the filling rich; a touch of gelatin keeps bars neat without tasting “jiggly.” Use semisweet chocolate for classic flavor or go darker for less sweetness.

Crust

• Graham crackers or digestives, crushed — 200 g (≈ 2 cups crumbs)
• Unsalted butter, melted — 85 g (6 tbsp)
• Granulated sugar — 25 g (2 tbsp, optional)
• Fine salt — 1 g (¼ tsp)

Custard Filling

• Whole milk — 500 ml (2 cups)
• Egg yolks — 4 large (≈ 70–80 g)
• Granulated sugar — 100 g (½ cup)
• Cornstarch — 30 g (¼ cup)
• Fine salt — 1 pinch
• Unsalted butter — 28 g (2 tbsp)
• Vanilla paste or extract — 2 tsp
• Powdered gelatin — 5 g (1½ tsp) + 45 ml (3 tbsp) cold water to bloom

Ganache

• Semisweet chocolate, finely chopped — 180 g (≈ 1 cup chips or 6 oz)
• Heavy cream — 180 ml (¾ cup)
• Unsalted butter — 14 g (1 tbsp, optional for shine)

Swaps: Use gluten-free 1:1 cookies by weight for the crust; lactose-free whole milk works in the filling; 54–60% chocolate keeps sweetness balanced (go 70% for bolder).

Step-by-Step (Timing, Visual Cues, Pan Size)

Line a 20 cm / 8-inch square pan (or 23 cm / 9-inch for thinner bars) with parchment, overhanging two sides.

1. Make the crust (5 min + chill 10–15 min).
   Stir crumbs, melted butter, sugar, and salt until the texture feels like damp sand. Press firmly into an even layer (use a flat-bottom glass). Freeze 10–15 minutes until cool and set.
2. Bloom gelatin (5 min).
   Sprinkle gelatin over 45 ml / 3 tbsp cold water. Let stand until sponged.
3. Cook the custard (10–12 min).
   Whisk yolks, sugar, cornstarch, and salt until thick and pale. Heat milk in a saucepan over medium until steaming. Slowly whisk hot milk into yolks, then return to the pot. Cook, whisking, until thick bubbles “blorp” and the whisk leaves tracks, 82–85 °C / 180–185 °F—keep whisking 1 minute more. Off heat, whisk in butter and vanilla. Stir in the bloomed until dissolved. Strain into a bowl.
4. Set the custard (2 hours).
   Let cool 5–10 minutes until hot-but-pourable (≈ 50–55 °C / 122–131 °F). Pour over crust, smooth the top, and refrigerate 2 hours until lightly springy.
5. Ganache (10 min + chill 45–60 min).
   Heat cream just to a simmer (edges bubbling, 80–85 °C / 176–185 °F). Pour over chocolate; stand 2 minutes. Stir from center until glossy; add butter if using. Cool to 32–35 °C / 90–95 °F so it doesn’t melt the custard, then pour and tilt to level. Chill 45–60 minutes until set but soft.
6. Slice cleanly.
   Lift with parchment, score portions, then cut with a hot knife, wiping between cuts. Serve cold. For another bake-sale favorite, bookmark our Oatmeal Raisin Chocolate Chip Cookies.

Pro Tips & Troubleshooting

• Trust the temp: Pull custard at 82–85 °C / 180–185 °F and whisk 1 minute more to avoid raw-starch gumminess.
• Don’t skip the strain: It removes any eggy bits for ultra-smooth filling.
• Gelatin = tidy slices: 5 g is the sweet spot for tender, non-bouncy bars.
• Cool ganache slightly: Pouring near 32–35 °C / 90–95 °F prevents melting lines in the custard.
• Pan size counts: 20 cm / 8-inch makes taller bakery-style squares; 23 cm / 9-inch sets faster and slices thinner.
• Condensation hack: Cover during chilling, but keep wrap off the surface to avoid water drops.

Variations & Budget-Friendly Ideas

Want a more “cake-like” vibe? Lay a single layer of plain tea biscuits or ladyfingers over the crust before the custard. Prefer darker chocolate? Use 200 g chocolate to 160 ml cream for a firmer, snappier top.

• Chocolate-Custard Bars: Whisk 20 g (3 tbsp) cocoa into the cornstarch mixture; add 30 g (2 tbsp) extra sugar.
• Pudding Shortcut: Whisk 2 boxes (≈102 g each) instant vanilla pudding with 720 ml (3 cups) cold milk + 120 ml (½ cup) cream; set 5 minutes, then spread (skip stovetop and gelatin).
• Mini Cups: Press 2 tbsp crust into lined muffin tins, add 3 tbsp custard, top with 1 tbsp ganache; chill 60–75 minutes.
  If you’re keeping things light for brunch, pair a small square with our Tropical Smoothie Açaí Bowl.

Storage, Make-Ahead & Reheat

• Fridge: Cover and refrigerate up to 3–4 days.
• Freeze: Not ideal for custards, but acceptable for parties—wrap the slab well and freeze up to 1 month. Thaw overnight in the fridge; dab any surface moisture before serving.
• Make-Ahead: Build the crust a day early; cook custard and assemble up to 24 hours ahead; add ganache the day of serving for the glossiest finish.

FAQs

Can I skip the gelatin?

Yes—bars will be softer. For clean, tidy squares (especially in warm rooms), keep the 5 g (1½ tsp) gelatin.

Can I use milk chocolate for ganache?

You can, but reduce cream to 150 ml (⅔ cup) for a similar set, since milk chocolate is softer and sweeter.

Why is my custard runny?

It wasn’t cooked long/hot enough or the cornstarch wasn’t activated. Next time, hit 82–85 °C / 180–185 °F and whisk 1 minute after bubbling.

Sources & Further Reading

• Serious Eats—clear pastry-cream technique, starch vs. egg thickening explained.
• King Arthur Baking—reliable ganache ratios and troubleshooting for set/shine.
• USDA Food Safety—custard and egg handling/chilling guidance for safe storage.

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