In a large frying pan over medium-high heat, heat oil until shimmering. Add onion and cook, stirring occasionally, for about 5 minutes until soft. Then add bacon and continue cooking, stirring occasionally, for another 5 minutes until crispy and browned. Remove from heat and let cool before proceeding.
Preheat the oven to 200C/180C fan-forced. Place a baking tray in the oven to heat up. Grease a 6cm-deep, 20cm round (base) springform pan. Use the base of the pan to cut out 1 circle from 1 pastry sheet. Line the base of the prepared pan with the pastry round. Cut the remaining pastry sheet into 3 equal strips. Line the sides of the pan with pastry, trimming to fit and pressing the edges together. You will have some extra pastry leftover.
Spread half of the bacon mixture evenly in the pan. Top with 1 cup of cheese. In a jug, whisk together 4 eggs and cream. Pour the mixture into the pan. Sprinkle the remaining bacon mixture over the top. Create 4 wells in the mixture and crack an egg into each one. Sprinkle the remaining cheese on top and season with pepper. Fold 1cm of pastry over at the top edge.
Place the hot tray in the oven and bake the pie for 45 to 50 minutes until firm to the touch. If the pie is over-browning, cover it loosely with foil. Let it stand in the pan for 10 minutes before serving.