Preheat oven to 350 F.
Divide cupcake batter evenly between two 7.4 x 7.2 x 2.3 inch heart-shaped silicone baking pans. (If you don't have these pans, you can substitute any pans with a four cup volume. However, depending on the depth, baking times may vary.)
Bake for 40 minutes or until a toothpick inserted into the center of each cake comes out clean.
Turn cakes out to a cooling rack to cool. Wash and dry cake pans thoroughly.
Blend strawberries and milk in a blender until fully combined.
Pour 1/3 of the strawberry mixture into a heatproof bowl.
Sprinkle gelatin on top, a little bit at a time, whisking well after each addition. Be sure to evenly distribute gelatin when you are sprinkling so as to avoid clumps.
Place the bowl over a pot of simmering water and whisk until gelatin completely dissolves.
Return contents of the bowl to the blender along with the cream cheese and blend to combine with remaining strawberry mixture.
Pour into a medium-sized bowl, cover in plastic wrap, and refrigerate for 10 to 15 minutes or until the mixture thickens to the consistency of Greek yogurt.
Whip heavy whipping cream and powdered sugar until soft peaks form.
Gently fold whipped cream into strawberry mixture a little bit at a time until fully incorporated.
Pour strawberry mousse into the bottom of each cake pan, filling to about one inch. (If you are using a pan that isn't silicone, line the pan with plastic wrap pulled as smoothly as possibly). Cover with plastic wrap and freeze for 15 minutes. Cover the remaining mousse with plastic wrap and refrigerate.
Cut each vanilla cake into three thin layers for a total of six layers. You'll only need four of the six layers. (I trust that you can find something to do with the extra ones. Eating them immediately comes to my mind.)
Trim the border of the four cake layers by about 1/4 inch.
Place a layer of cake on top the mousse layer in each cake pan.
Top with another layer of mousse.
Top each with the remaining cake layer.
Cover with remaining mousse and level with a bench scraper.
Cover with plastic wrap and freeze overnight.
Unmold and bring to room temperature before serving.