Preheat the oven to 370F (185C) and line the muffin pan with 9 muffin liners. Set aside.

Heat a little bit of oil in a non-stick skillet over a medium heat. When hot, add the bell pepper, season with salt and pepper, and cook until softened. Then, add the spinach and cook for one more minute. Remove from the heat into a bowl or onto a plate to cool down a little bit.

To the same skillet, add the bacon and cook until golden brown and crisp. When done, remove onto a paper towel to cool down. When safe to handle, crumble.

Put the eggs, heavy cream, parmesan cheese in a large bowl. Season with salt and pepper, then whisk well.

Add the vegetables and bacon and whisk until incorporated. Divide the mixture between the muffin liners (around ⅓ cup/each) and bake for around 15 minutes or until set and golden on the top.

Remove from the oven and let cool down to warm before serving.