Set up your dish: Use a 2–2.5 quart dish or 8x8-inch pan. Have your cookies and sliced bananas ready. If you like, toss banana slices lightly with lemon juice to slow browning.

Whisk the base: In a medium bowl, whisk egg yolks, sugar, cornstarch, and a pinch of salt until smooth and pale. This prevents lumps later.

Heat the dairy: In a saucepan, warm the milk (and heavy cream if using) over medium heat until steaming but not boiling. Stir often so it doesn’t scorch.

Temper the eggs: Slowly pour about 1 cup of the hot milk into the yolk mixture while whisking constantly. Then pour the tempered mixture back into the saucepan.

Cook the pudding: Cook over medium heat, whisking steadily, until it thickens and bubbles—about 3–5 minutes. Once it bubbles, cook 30–60 seconds more to fully activate the cornstarch.

Finish with flavor: Remove from heat. Whisk in butter and vanilla. Taste and adjust vanilla if needed.

Cool slightly: Let the pudding sit for 5 minutes, whisking once or twice to release steam. This keeps it silky.

Layer: Add a layer of cookies to the dish, then a layer of banana slices, then a layer of warm pudding. Repeat 2–3 times, ending with pudding on top.

Top it off: Spread whipped cream over the final layer. Crush a few cookies and sprinkle on top for a little crunch.

Chill: Cover and chill at least 4 hours, or overnight for the best texture. The cookies soften and the flavors meld.

Serve: Scoop into bowls or slice and lift out squares. Add extra banana slices or a drizzle of caramel if you like.