Vanilla cake: Preheat the oven to 350 degrees. Prepare two 9x13” pans by spraying with non-stick spray, then line with parchment (the non-stick helps the parchment to stay down), and spray the parchment with non-stick spray.
In the bowl of a stand mixer, cream butter and sugar until light and fluffy. Beat in eggs until well combined. Add milk and vanilla and beat until smooth.
Add flour, baking powder and salt and mix just until combined and smooth.
Divide between both pans – you want an even, thin layer in both pans.
Bake for 20-25 minutes, or until a toothpick inserted in the center comes out clean or with moist crumbs (baking time will vary based on pan size, so be sure to check often).
Cool completely. Then you can either freeze the cakes (as I mentioned above) or cut out your mini cakes with a regular biscuit cutter (about 2.5” diameter).
Strawberry Meringue Frosting: Puree strawberries in a blender or food processor (I used a Magic Bullet because it gets things the smoothest for me). Set aside.
In the bottom of your double broiler (see notes and photo above in post if you do not have one), put about ½ - 1” of water (make sure that the bottom of your bowl will not touch the water when it’s boiling). Set on the stove and bring to a boil.
In the top of your double broiler (your bowl), off the heat, whisk together the sugar and egg whites. Place over your pot of boiling water and reduce heat to medium or medium-low. Continue cooking and whisking until the mixture reaches 160 degrees F and sugar is dissolved (this took a while for me – 10-15 minutes).
Pour mixture into the bowl of a stand mixer and whip with a whisk on medium-high speed until stiff peaks form and mixture is room temperature (about 10 minutes).
Add butter, one cube at a time, beating until incorporated. Add the pureed strawberries gradually, making sure that they do not dilute your frosting and make it runny (I used the full amount and it was not runny at all – this is just a precaution). Beat until combined (if your frosting begins to look soupy or curdled after adding the butter and strawberries, continue beating 3-5 minutes on medium-high and it will come together! This happens every time I make it).
If you find that it’s not as sweet as you hoped, add in optional powdered sugar.
Frost cakes as desired. Store in the refrigerator or freezer until ready to serve.