Preheat the oven to 350F. Line two, 8-inch cake pan with parchment paper.
In a large mixing bowl, cream together the butter, sugar and vanilla for a few minutes until creamy. Add the egg yolks and milk and mix again for 1 to 2 minutes, until well-combined.
In a separate bowl, combine the dry ingredients: flour, almond flour, baking powder and salt. Sift the dry ingredients into the cake batter and mix for 1 minute, until combined.
In a separate bowl, whisk the egg whites with 1/4 tsp cream of tartar for 4 to 5 minutes, until stiff peaks form. Fold the egg whites into the batter gently.
In a separate bowl, combine the 1 cup diced strawberries and 1 cup diced rhubarb with cornstarch. Toss the fruit in the starch, then fold into the batter.
Baking Instructions:
Divide the batter between the two pans and bake in preheated oven at 350F for 28 to 30 minutes, until the cake layers are golden brown. Remove from the oven, out of the cake pans, and cool completely on a wire rack.
Making the Jam:
Meanwhile, prepare the jam. Combine the diced rhubarb, strawberries and sugar in a medium-sized sauce pot. Cook over medium heat and bring to a simmer; simmer for 8 to 10 minutes, until the diced rhubarb breaks apart to form a puree. Allow the jam to cool completely before using in the cake.
Making the Frosting:
Prepare the whipped cream next: combine the chilled cream, sugar and vanilla in a mixer bowl. Whisk on medium-high speed for 4 to 5 minutes, until stiff peaks form.
Assembling the Cake:
Assembled the cake once the layers and jam have cooled completely. Spread a generous amount of whipped cream between the two layers, along with spoonfuls of jam. Top the cake with more whipped cream, jam and sliced strawberries. Keep refrigerated if not serving immediately.