Get the oven ready: Turn your oven on to 375 degrees Fahrenheit.

Prepare your pans: You can use 5 small oven-safe bowls (ramekins) or one 9-inch round cake pan. Line the bottom and sides of each pan with parchment paper. This helps the cakes come out easily.

Make the sweet butter layer: In a small bowl, mix the ½ stick of softened butter and the ⅓ cup of sugar together with a fork until it's combined. Spread this mixture in a nice, even layer on the bottom and up the sides of your prepared pans. Set them aside.

Mix the dry stuff: In another bowl, whisk together the cake flour, baking powder, and salt. This helps everything get evenly mixed.

Cream the butter and sugar: Using an electric mixer (handheld or stand mixer), beat the remaining 1 ½ sticks of softened butter and the 1 cup of sugar together until the mixture looks light and fluffy. This usually takes about 5 minutes.

Add the eggs and vanilla: Add the whole egg, the egg yolk, and the vanilla extract to the butter and sugar mixture. Beat until everything is just combined.

Mix in the flour and milk: Turn your mixer to a low speed. Slowly add the flour mixture and the milk to the batter, alternating between them. Start with some flour, then some milk, then more flour, and so on. Mix until everything is just combined. Be careful not to overmix!

Pour in the batter: Divide the batter evenly among your prepared pans.

Bake until golden: Bake for 35 to 45 minutes. The cakes are done when they look golden brown and a toothpick or fork inserted into the center comes out clean.

Cool and flip: Once the cakes are out of the oven, let them cool in the pans for about 10 minutes. Then, carefully turn them out upside down onto a plate. Remove the parchment paper and let the cakes cool completely.

Warm the jam: Put the raspberry jam in a small microwave-safe bowl and heat it in the microwave for about 30 seconds, until it's a little runny.

Add the finishing touches: Pour some of the warmed raspberry jam over each cooled cake and top with a dollop of whipped cream. Enjoy!