Combine flour, sugar, baking powder, and salt in food processor.

Incorporate butter and oil. Add water and mix with pulses until ingredients are fully integrated.

Remove dough from food processor and finish mixing it with your hands until it gets soft and tender. On a floured surface roll dough with a rolling pin until big enough for pie dish. Place on pie dish and remove excess. Place pie crust in the refrigerator covered for at least 20 minutes.

Prepare the filling. Sauté in oil and butter the leeks at medium low temperature covered, stirring occasionally, for 15 minutes. Do not let the leeks burn; if necessary add some water. Add garlic and cook for another minute. Remove from heat.

Preheat oven to 375F.

Beat eggs and yolks. Add milk and pepper. Mix in milk. Add leeks and combine.

Add cheese and mix well. Pour on crust.

Bake for 35 minutes.