1-First, prepare the cookie shells: Line a baking sheet with parchment paper and place 4-inch tart tins spaced apart; spray them if you want extra assurance they won’t stick. Cream 1 cup salted butter and 2 cups granulated sugar together until well combined. Add 2 large eggs and beat until creamy, then mix in ½ cup canola or vegetable oil and 1 tablespoon vanilla extract until the mixture is light and fluffy.

2-Next, sift in 4¼ cups all-purpose flour, 2 teaspoons cornstarch, 1½ teaspoons baking powder, and 1 teaspoon salt, then beat until you form a soft dough. Scoop about ¼ cup dough into each tart tin and press firmly to create a well without any holes. Chill in the refrigerator for 15 minutes, then preheat your oven to 350°F. Bake for 12-15 minutes until the edges turn golden; tap the pan to deflate any puffed centers if needed. Let them cool in the tins first, then fully on a rack.

3-While the cookies cool, make the pastry cream: In a saucepan, whisk together 1 cup granulated sugar, 3 cups whole milk, 1 cup heavy cream, 8 egg yolks, ½ cup cornstarch, and ¼ teaspoon salt. Heat over medium heat, whisking frequently, until it simmers and thickens; let it boil for 30-60 seconds. Strain to remove any bits, then add 4 tablespoons salted butter and 1 teaspoon vanilla extract, whisking until smooth. Cover with plastic wrap pressed on the surface and chill until cold.

4-For the chocolate ganache, heat ⅓ cup heavy cream until simmering, then pour it over ⅓ cup semisweet chocolate chips and let it sit for 1-2 minutes. Whisk until smooth, add 2 tablespoons salted butter, and stir until incorporated. Cool for 5-10 minutes until it’s pourable but not too runny.

5-Finally, assemble the cookies: Spoon the chilled pastry cream into the cooled cookie wells, mounding it slightly. Drizzle the ganache over the cream and let it run naturally. Chill the assembled cookies for 1-2 hours before serving. For more tips on perfecting your bakes, visit tips to improve your next batch of cookies.