Preheat oven to 300°. Spray 8 (2-ounce) ramekins with baking spray. Arrange ramekins on a jelly-roll pan.
Combine butter, 1/3 cup sugar, rum, and egg yolks in the bowl of a stand mixer fitted with a paddle attachment; beat at medium speed 3 minutes. Scrape seeds from vanilla bean into butter mixture; discard bean. Whisk together flour, custard powder, and baking powder in a medium bowl. Reduce mixer speed to low. Add flour mixture to butter mixture in 2 additions; beat at low speed 2 minutes or until thoroughly combined. Transfer mixture to a large bowl, scraping mixing bowl clean with a rubber spatula. Clean and dry mixing bowl.
Add egg whites to bowl of stand mixer fitted with a whisk attachment. Beat egg whites at medium-high speed 2 minutes or until soft peaks form. With mixer running, slowly add remaining 1/3 cup sugar to mixing bowl. Beat 1 minute or until stiff peaks form. Fold egg whites into cake batter using a rubber spatula.
Divide batter among prepared ramekins. Bake 18 to 20 minutes or until a skewer inserted in center comes out with dry crumbs. Cool cakes completely in ramekins.
Pierce cakes 4 to 5 times with a skewer. Drizzle 1 tablespoon Soaking Syrup evenly over each cake. Let stand 10 minutes.
Whip crème fraîche with a hand mixer 1 minute or until soft peaks form.
Carefully loosen edges of cakes with a knife. Invert each ramekin onto a serving plate; gently lift ramekin from cake. Sprinkle surface of each cake evenly with 1 teaspoon turbinado sugar. Holding a kitchen blowtorch about 2 inches from the top of each cake, evenly heat the sugar, moving torch back and forth, 1 minute or until sugar is completely melted and caramelized. Serve cakes immediately with whipped crème fraîche and Strawberry Salad.