Preheat oven to 375°F. Coat an 8-inch round cake pan with baking spray; line bottom of pan with parchment paper. Fill a medium saucepan with water to a depth of 1 inch; bring to a boil over medium-high, and reduce heat to medium-low to maintain a simmer. Place chocolate and oil in a medium-size heatproof bowl; set bowl over the pan of simmering water, making sure the bottom of the bowl doesn’t touch the water. Cook over medium-low, stirring occasionally, until chocolate is melted and mixture is smooth, 6 to 7 minutes. Set aside until cool to the touch, about 5 minutes.

Meanwhile, beat egg yolks and sugar in a medium bowl with an electric mixer on high speed until thickened and pale, 2 to 3 minutes. Stir in almond flour and cayenne pepper, if using; mix until combined. Fold melted chocolate mixture into egg yolk mixture in bowl until well combined.

Beat egg whites and fine sea salt in a separate medium bowl with an electric mixer on high speed until medium peaks form, 1 to 2 minutes. Working in 2 batches, fold whipped egg whites into chocolate mixture until no streaks remain, being careful not to deflate egg whites. Pour batter into prepared cake pan, and smooth using a spatula.

Bake until cake is mostly set with a slightly jiggly center, 12 to 13 minutes. Let cake cool on a wire rack for 10 minutes; transfer to refrigerator to chill completely, 1 to 2 hours. Sprinkle flaky sea salt over top; serve with a dollop of whipped cream.