Preheat oven to 350 degrees F. Grease a 9x13-inch baking pan. Set aside.

In a large mixing bowl, beat together the butter and sugar until light and fluffy. Add the oil, vanilla extract, and lemon zest and blend well. Mix in eggs until well combined. Blend in the 1/2 cup of fresh lemon juice.

On low speed, baking powder, baking soda, salt and half of the flour until just combined. Blend in the milk then the remaining flour. Do not overmix.

Pour batter into prepared pan and bake uncovered for 30-40 minutes until a toothpick inserted into the center comes out clean.

Remove the cake from the oven and use a skewer or the round end of a wooden spoon to poke holes every inch or so across the cake, pressing about 2/3 of the way into the cake.

In a small bowl, blend together the sweetened condensed milk and 1/2 cup of fresh lemon juice and pour the mixture over the hot cake. Try to get as much of the filling as you can into the holes.

Allow the cake to cool at room temperature for at least 30 minutes.

To make the lemon mascarpone whipped cream, start by whipping the heavy whipping cream and powdered sugar until stiff peaks form. Add the mascarpone cheese, lemon juice, and vanilla extract and blend until smooth and silky. Spread or pipe the topping over the cooled cake.