Preheat the oven to 350°F (180°C). Butter and line two 8-inch pans and set aside.

In a medium bowl, whisk flour, baking powder and salt together. Set aside.

In a separate small bowl, combine jam, sour cream and vanilla extract. Set aside.

In the bowl of a stand mixer fitted with a paddle attachment, cream the butter and sugar together for 5 minutes on high speed, until light and fluffy.

Slowly whisk in the egg whites one at a time until blended. Scrape down the sides of the bowl once or twice to ensure even blending.

Mix in 1/3 of the flour mixture, followed by ½ of the sour cream mixture. Continue alternating until the batter is just combined. Finally stir in food coloring if using.

Bake for about 30 minutes, or until a tester inserted in the center of the cake comes out clean. Let cool for 10 minutes before transferring the layers to a wire rack to cool completely.

Stir the strawberries, jam and lemon juice together and let macerate in the refrigerator for 30 minutes.

If the layers are domed, first slice to tops to make them flat.

Place the bottom layer on a serving plate and spread a thin layer of frosting on top, creating a small dam around the edge to hold in the filling.

Scoop on the macerated strawberries, leaving as much of the liquid behind in the bowl as you can. Then place on the top cake layer, bottom side up.

Cover the top and sides of the cake with a thin layer of frosting to create a crumb coat and refrigerate for 30 minutes to let the frosting harden,

Finish with a second, decorative layer of frosting to cover the crumb coat and serve right away or refrigerate until ready to serve.

Store leftovers in an airtight container in the refrigerator for up to 2 days.