Preheat your oven to 350°F (175°C). In a large mixing bowl, combine the white cake mix, granulated sugar, water, eggs, vegetable oil, and vanilla extract. Mix on medium speed until well combined, about 2 minutes. Gently fold in the all-purpose flour, kosher salt, and full-fat sour cream until the batter is smooth and creamy.

Divide the batter evenly between two greased sheet pans, spreading it out evenly with a spatula. Place the pans in the oven and bake for 15-18 minutes, or until the cakes are lightly golden and a toothpick inserted in the center comes out clean. Once baked, remove from the oven and let the cakes cool in the pans for about 30 minutes. Transfer them to the refrigerator for further chilling.

While the cakes cool, prepare the marshmallow filling. In a mixing bowl, beat the marshmallow crème and salted butter together until fluffy, about 3-4 minutes. Gradually add the powdered sugar and vanilla extract, mixing until smooth. Drizzle in the heavy cream and beat until the filling reaches a spreadable consistency.

Once cooled, carefully cut out heart shapes using a cookie cutter from each cake. Spread a generous layer of marshmallow filling on the flat side of half of the heart-shaped cakes. Top with the other halves, pressing gently. Place the cakes in the freezer for about 1 hour to firm up.

Melt the almond bark in a double boiler, stirring often for even melting. Mix in the Crisco for a smooth finish. Add pink gel food dye and mix well.

Retrieve the chilled heart cakes from the freezer and dip each into the melted pink almond bark. Allow excess to drip off, then place the coated cakes on parchment paper to set. Optionally, drizzle reserved melted almond bark or additional white chocolate over the top for an appealing finish. Leave the cakes to cool until the coating hardens completely.