Preheat the oven to 350°F. Prepare three 8-inch round baking pans, line the bottom with parchment paper, and grease the sides.

In a large mixing bowl, combine the sugar, vegetable oil, eggs, and vanilla extract. Beat on medium speed until well incorporated, about 2 minutes.

Mix in the sour cream and beat until well combined.

Combine the dry ingredients in a separate bowl. Add half the dry ingredients and beat on low speed while pouring in half of the milk.

Add the remaining dry ingredients, mixing on low speed while pouring in the remaining milk and beat until well combined.

Divide the batter evenly between the three pans, about 1 ⅔ cups of batter per pan. Bake at 350°F for 20-23 minutes.

Test for doneness by inserting a toothpick into the center of the cake. If it comes out clean, the cake is done. Allow to cool completely.

Chop and puree the strawberries using an immersion blender or food processor.

In a medium-sized saucepan, combine the flour and sugar. Add the pureed strawberries and lemon juice. Cook over medium-high heat until boiling.

Reduce heat and simmer for 5-10 minutes until thickened. Add up to 1 tablespoon of additional flour if too thin.

Allow the puree to cool completely, refrigerating to speed up the process.

Place the mixing bowl and whisk attachment in the freezer for 5 to 10 minutes to chill.

Spoon the cold mascarpone whipped cream into your bowl and beat on medium-low speed while slowly pouring in the heavy cream.

Increase the mixing speed to high and beat until soft peaks form.

Add the powdered sugar and vanilla extract, beating on low until sugar is incorporated. Then continue beating until stiff peaks form.

Use a cake leveler to cut the domes off the top of the cake. Place a dollop of frosting on your cake board and place the bottom layer of cake on top.

Pipe a thick border along the outside edge of your cake with half of the whipped cream.

Spread half of the strawberry mixture over the cake, filling the inside of the dam carefully.

Pipe another thin layer of frosting over the strawberry sauce and spread it evenly.

Add the second layer of cake and repeat the above steps using all of the remaining strawberry sauce.

Add the final layer of cake on top.

Fill in any gaps between the layers with piping bag frosting and create a crumb coat.

Frost the top and sides of the cake using an offset spatula and remove excess frosting.

Use the remaining frosting to pipe florets on top and garnish with leftover strawberries. Refrigerate the cake.