Step 1: Bake the Cake Layer

1. Preheat your oven to 350°F (175°C). Grease and line an 8×8-inch baking pan with parchment paper.

2. Mix Dry Ingredients: In a bowl, whisk together flour, baking powder, and salt.

3. Cream Butter & Sugar: In a large bowl, beat butter and sugar until light and fluffy.

4. Add Wet Ingredients: Mix in eggs one at a time, then stir in vanilla.

5. Combine Mixtures: Alternate adding dry ingredients and milk, stirring just until combined.

6. Bake: Pour batter into the prepared pan. Bake for 25–30 minutes, or until a toothpick inserted comes out clean. Let cool in the pan.

Step 2: Prepare the Cream Filling

1. Whip Cream: In a bowl, beat heavy cream, powdered sugar, and vanilla until soft peaks form.

2. Make Custard: In a saucepan, heat remaining cream until simmering. Mix cornstarch with cold water to form a slurry and whisk it in. Stir until thickened (1–2 minutes), then cool slightly.

3. Fold Together: Gently fold cooled custard into whipped cream. Chill until ready to use.

Step 3: Assemble the Bars

1. Layer Cream: Spread cream filling evenly over the cooled cake layer.

2. Chill: Refrigerate for 1 hour to firm up.

Step 4: Make Chocolate Ganache

1. Heat Cream: In a small saucepan, bring cream just to a simmer.

2. Add Chocolate: Pour hot cream over chocolate chips in a bowl. Let sit for 1 minute, then stir until silky and smooth.

Step 5: Top and Serve

1. Finish Bars: Pour ganache over the cream layer. Use a spatula to spread evenly.

2. Final Chill: Return to the fridge for at least 1 hour.

3. Slice & Serve: Cut into squares and serve cold for clean, gorgeous layers.