First Step: Prepare Your Baking Pans and Oven. Preheat your oven to 350°F (177°C). Grease and flour two 8-inch round cake pans or line them with parchment paper to ensure easy removal of the cake layers.

Second Step: Mix Dry Ingredients. In a large bowl, whisk together the all-purpose flour, baking powder, baking soda, and salt until well combined.

Third Step: Cream Butter and Sugar. In a separate large bowl, beat the softened butter and granulated sugar together until the mixture becomes creamy and smooth, typically about 2-3 minutes with an electric mixer.

Fourth Step: Add Wet Ingredients. Gradually add the vegetable oil and eggs one at a time to the creamed butter and sugar, mixing well after each addition. Next, stir in the vanilla extract and milk slowly while continuing to mix.

Fifth Step: Combine Wet and Dry Ingredients. Add the dry ingredient mixture to the wet ingredients gradually, mixing just until combined. Be careful not to overmix to maintain a tender cake texture.

Sixth Step: Bake the Cake. Divide the batter evenly between the prepared pans and bake for 25-30 minutes, or until a toothpick inserted into the center comes out clean or with moist crumbs. Adjust baking time slightly if using gluten-free flour blends.

Seventh Step: Prepare the Lemon Crumb Topping. While the cake bakes, preheat the oven to 350°F (177°C). Spread the flour on a parchment-lined baking sheet and bake for 5 minutes. Let it cool. In a mixing bowl, combine the cooled flour, powdered sugar, and cold butter, cutting in the butter using a pastry cutter or fork until small crumbs form. Stir in lemon zest and vanilla extract. Chill the crumb topping for about 1 hour before use.

Eighth Step: Prepare the Lemon Mascarpone Cream Filling. Whip cold heavy cream to stiff peaks using chilled beaters and bowl for best results. In a separate bowl, mix together mascarpone cheese, powdered sugar, lemon zest, and fresh lemon juice until smooth. Gently fold the whipped cream into the mascarpone mixture until fully incorporated. Refrigerate the filling until needed.

Final Step: Assemble the Cake. Once cooled, optionally slice each cake layer horizontally to create additional layers. Spread a generous amount of lemon cream filling between layers and on the top and sides of the cake. Press the chilled lemon crumb topping evenly onto the sides and top of the cake. Just before serving, dust lightly with powdered sugar.