Preheat the oven to 350° F.
Heat the olive oil and butter in a large skillet until the butter melts. Add the onions and sauté, stirring occasionally, until translucent and golden, about 15 minutes.
Meanwhile, roll out the pie crust and press it in a baking dish that is about 1 ¼” inches deep and 9” in diameter. Prick the dough slightly with a kitchen fork. Place aluminum foil of a piece of parchment paper over and fill it with pie weights, rice, or dry beans. Bake it for 12 minutes. Remove weights and paper and set them aside.
In a small skillet cook the bacon until crisp. Drain on a paper towel and set aside.
Whisk together in a large bowl, the heavy cream, eggs, season with salt and pepper. Stir in the reserved bacon, the caramelized onions, and ½ cup provolone cheese into the egg mixture. Mix well and pour it evenly into the pie crust. Sprinkle the remaining pecorino cheese over the top. Cover the edges with a pie shield or aluminum foil to prevent burning.
Bake in the warm oven for 40 minutes, the top of the tart turns into a golden color, and the blade of a knife comes out clean. Remove from the oven and let it cool off on a wire rack.
Serve at room temperature.