Instructions

for the topping

Adjust oven rack to middle position and heat oven to 350 degrees. Spray 6-inch cake pan with baking spray with flour, line bottom with parchment paper, and grease parchment. Melt 2 tablespoons unsalted butter in 8-inch nonstick skillet over medium-low heat. Add 1¼ cups cranberries, ⅓ cup (2⅓ ounces) sugar, and 1 tablespoon seedless raspberry jam and cook, stirring gently, until cranberries are just softened, about 3 minutes. Off heat, stir in ⅛ teaspoon vanilla. Pour berries with juice into prepared pan, gently spread into even layer, and refrigerate for 30 minutes.

for the cake

Whisk ½ cup (2½ ounces) all-purpose flour, ½ teaspoon baking powder, and ⅛ teaspoon table salt together in medium bowl. Whisk ¼ cup whole milk and ½ teaspoon vanilla together in separate bowl.
Using stand mixer fitted with paddle or using hand mixer, beat 3 tablespoons softened unsalted butter and ⅓ cup (2⅓ ounces) sugar together on medium-high speed until pale and fluffy, 3 to 4 minutes, scraping down bowl as needed. Add 2 large egg yolks, one at a time, and beat until combined, scraping down bowl after each addition. Reduce speed to low and add flour mixture in 3 additions, alternating with milk mixture in 2 additions, scraping down bowl as needed. Give batter final stir by hand, then transfer batter to large bowl.
Using clean, dry mixer bowl and whisk attachment or using hand mixer, whip 1 large egg white and pinch cream of tartar on medium-low speed until foamy, about 1 minute. Increase speed to medium-high and whip until soft peaks form, 2 to 4 minutes, scraping down sides of bowl occasionally. Whisk one-third of whipped white into batter, then add remaining white and gently fold into batter until no white streaks or lumps remain.
Pour batter over chilled cranberry mixture and smooth top. Bake until toothpick inserted in center of cake comes out clean, 35 to 40 minutes, rotating pan halfway through baking. Let cake cool in pan on wire rack for 10 minutes. Run paring knife around edge of cake and invert onto serving platter; remove parchment. Serve warm or at room temperature.