The first step is to make the dulce de leche, which takes time and a watchful eye but is really quite simple—and it’s delicious homemade. Remove the label and glue from the can of condensed milk—otherwise paper and glue can make for a very messy cleanup. Place the cleaned, still-sealed can on its side in a heavy-bottomed pot. Fill with enough water to cover can by 2 inches. Bring water to a rapid simmer and simmer for 3 hours, being sure to keep adding hot water to keep the can completely submerged by 2 inches during the entire cooking process. After 3 hours, using tongs, remove can from the pot and cool at room temperature for at least 1 hour before opening. (Cooling is an important safety step. Dulce de leche may be made in advance and stored at room temperature—the sealed can is shelf stable.)

For the tart shell, sift together flour and cocoa powder to remove any lumps and set aside. In a stand mixer fitted with a paddle attachment, mix 1 stick (8 tablespoons) butter with confectioners’ sugar until pale yellow and fluffy, about 3 minutes, scraping down the bowl as needed. Slowly add egg yolks, then vanilla, and mix until incorporated, scraping down the bowl. Gradually add dry ingredients, ⅓ at a time. Finish by mixing in the ice water.

Turn dough onto a lightly floured surface and shape into a 5-inch disk. Wrap in plastic; refrigerate 1 hour. Preheat oven to 350°F. On a floured surface, roll dough into a 9-inch by ¼- inch-thick circle. Center the dough over an 8-inch fluted tart pan with a removable bottom. Press around the bottom and evenly up the sides to create side walls to hold the filling. Using a fork, prick the bottom of the shell all around to allow air to release while baking. Blind bake the shell on the middle rack for 12 minutes, rotating after 6 minutes. Remove from oven and allow to cool completely before removing the rim.

Lastly, make the ganache. Place chocolate in a heat-proof mixing bowl. In a small pot, bring cream (or milk) to just below boiling and remove from heat. Pour hot cream into the bowl and stir until chocolate is melted. Stir in remaining 8 tablespoons (1 stick) butter, 1 tablespoon at a time, to create a silky chocolate sauce.

To assemble, place the chocolate shell on a serving plate, pipe in the dulce de leche from the edge to the middle in a spiral clockwise motion. Using a small offset spatula or butter knife, gently spread to create a flat surface. Spoon in the warm ganache with a last large dollop in the middle. In a counterclockwise motion working from the middle to the shell edges, slowly spread the ganache until smooth. Sprinkle flaky sea salt atop the ganache to taste. Serve with a dollop of whipped cream and enjoy!