Start with the raspberry heart cake. Preheat the oven to 350 degrees F.
Mix the butter and sugar in the bowl of a stand mixer until incorporated, about 2-3 minutes. While waiting, using a food processor, blitz the flour, dried raspberries, salt and baking powder together. Set aside.
Slowly, with the mixer on low, add the eggs to the stand mixer mixture one egg at a time. Scraping down the bowl after they've been added. Add in the sour cream, vanilla and optional food coloring.
Once the wet ingredients are mixed together, with the mixer on low, add the flour mixture and mix until just incorporated.
Pour raspberry cake batter into a greased and floured 9x13in pan. Bake until cooked all the way through, about 20 minutes.
While the raspberry cake bakes, make the lemon pound cake.
Mix the butter and sugar in the bowl of a stand mixer until incorporated, about 2-3 minutes. While waiting, mix the flour, lemon zest, salt and baking powder together. Set aside.
With the mixer on low, add the eggs one egg at a time. Scraping down the bowl after they've been added. Add in the sour cream and lemon juice. Once incorporated, add the dry ingredients. Set batter aside. In a separate bowl, mix the powdered sugar and lemon juice glaze and also set aside.
When the raspberry cake is done, cool completely then slice into heart shapes. Stack the hearts one on top of another.
Take the lemon pound cake batter and pour half of it into a greased bread pan. Place the stack of raspberry hearts in the center of the bread pan on top of the lemon pound cake batter. Then smother the hearts with the rest of the lemon pound cake batter.
Bake until cooked all the way through 40-45 minutes. Once cooled, top with the lemon glaze, slice and serve.