In a saucepan, combine the sugar, cornstarch, and salt. Whisk well.

Add the eggs and vanilla extract, then whisk until smooth.

Pour in the milk, and whisk again to combine.

Heat the mixture over medium heat, stirring continuously.

When it begins to boil, reduce the heat to low and cook for 1–2 minutes, until thickened to a

pudding-like consistency and no raw starchy taste remains.

Remove from heat and add the butter. Whisk until fully melted and combined.

Strain the mixture through a fine mesh sieve into a clean medium bowl to remove any curdled egg pieces.

Cover the surface with plastic wrap to prevent a skin from forming and refrigerate until chilled.

Preheat the oven to 320F (160C). Line the bottom and sides of an 8” x 8” (20cm x 20cm) brownie pan with parchment paper.

In a stand mixer with the paddle attachment (or use a hand mixer and a mixing bowl), cream together the white sugar, brown sugar, butter, and vanilla extract until light and fluffy.

Add the vegetable oil and mix until incorporated.

Add the egg and beat again.

Add the puréed bananas and mix until fully combined.

Sift in the flour, salt, baking powder, and baking soda. Mix on low speed until just incorporated. The batter should be thick.

Spread the batter evenly into the prepared pan and bake for 30–35 minutes, or until a toothpick inserted into the center comes out clean.

Let the cake cool in the pan until safe to handle. Then, remove the cake from the pan and wrap it in plastic wrap. Refrigerate until completely cooled.

Whip the heavy cream with powdered sugar using a hand mixer until stiff, shiny peaks form.

Using the same mixer, whip the chilled pastry cream until it’s smooth.

Gently fold one-third of the whipped cream into the pastry cream using a rubber spatula. Fold in the remaining whipped cream until fully combined and smooth.

Spread the cream evenly over the cooled cake, or transfer it to a piping bag for a decorative finish.

Refrigerate the assembled cake for at least 1 hour before serving.