In a small saucepan over low-medium heat, bring the milk to a simmer, or about 190 degrees F.

Meanwhile, in a medium bowl, vigorously whisk together the egg yolks, granulated sugar, and cornstarch until pale in color and the mixture flows off of the whisk.

Once the milk has reached a simmer, slowly pour half of it into the egg-sugar mixture while simultaneously whisking to temper the eggs. Pour everything back into the saucepan and place over medium heat. Use a rubber spatula to mix constantly as it thickens.

Once the pastry cream is thick and a few big bubbles come to the surface, continue whisking for one more minute, then remove the pan from heat.

Immediately pour the pastry cream through a fine mesh sieve into a small bowl to ensure it’s perfectly smooth. Then, add the butter and vanilla, and use an immersion blender (or rubber spatula) to combine.

Press plastic wrap up against the surface of the pastry cream to prevent a skin from forming, and place in the fridge to chill for at least one hour or until ready to use.

Just before you are ready to assemble the jars, make the whipped cream.

In a medium bowl, beat the heavy cream with an electric mixer while slowly pouring in the granulated sugar.

Beat until soft peaks form, and no more! It can be easy to over-whip, so watch carefully.

Add half of the whipped cream to the cooled pastry cream, and gently fold with a rubber spatula until fully combined. Reserve the other half for topping.

In each jar, add layers of pudding, nilla wafers, and fresh banana, then repeat until full.

Top each with a generous dollop of the reserved whipped cream, then place in the fridge overnight.