Preheat oven to 300F.
Core and cut the apples into slices about 1/4-inch thick. Toss the sliced apples with lemon juice, three tablespoons of sugar, a pinch of salt, and a pinch of cinnamon.
In a small bowl, whisk together the flour, semolina, cinnamon, salt, vanilla powder and the remaining sugar. In a larger bowl, combine the heavy cream lemon zest, and melted butter. Slowly add the dry ingredients until fully incorporated.
Spoon the mixture into greased tart shells (we use 4-inch shells) and top with the sliced apples. Carefully squeeze in as many apples slices as possible. Bake for about 25 minutes minutes, or until the apples are golden brown. Using an offset spatula, carefully lift the tart and check the bottom to ensure the tart is baked through.