Begin by greasing, flouring, and lining two 8-inch round cake pans with parchment paper to prevent sticking. Set your oven to preheat at 325°F (163°C).

In a mixing bowl, combine the cake flour, fine sea salt, baking soda, baking powder, and Dutch process cocoa powder. Whisk until well incorporated.

Add the brown sugar, flavorless oil, and milk to the dry ingredients, whisking until smooth. Then add the large egg and whisk until the batter is thick and glossy.

Pour the chocolate batter into the prepared pans, smoothing the tops. Bake for about 12 minutes or until a toothpick inserted comes out clean. Let cool in pans.

Prepare the vanilla ice cream layer by letting it sit at room temperature for about 10 minutes to soften.

In a clean 8-inch cake pan lined with plastic wrap, place one chocolate cake layer face down. Spread the softened vanilla ice cream evenly over this layer.

Place the second cake layer face up on top of the ice cream, pressing gently for a snug fit.

Cover the assembled cake tightly with plastic wrap and freeze overnight.

When ready to serve, invert the frozen cake onto a serving plate, remove plastic wrap, slice, and enjoy.