01 -
Dice the bacon if using. Peel and thinly slice the potatoes. Mince the garlic. Pick thyme leaves to yield 2 teaspoons. Grate the cheese if using.
02 -
Arrange an oven rack in the middle position and preheat to 200 °C.
03 -
In a medium or large bowl, whisk together the eggs (use 6 if including bacon and cheese), cream, and half the salt until well combined.
04 -
Place diced bacon in a cold 26–30 cm ovenproof nonstick frying pan or cast iron skillet. Cook over medium-high heat, stirring occasionally, until bacon is crisp, 8–10 minutes. Remove bacon with a slotted spoon to a paper towel-lined plate and reserve 2 tablespoons rendered fat in the pan. If omitting bacon, heat 2 tablespoons oil in the skillet before proceeding.
05 -
Return skillet to medium heat. Add potatoes, black pepper, and remaining salt. Sauté, stirring occasionally, until potatoes are tender and lightly browned, about 4–6 minutes.
06 -
Add minced garlic, thyme leaves, and baby spinach to the pan. Cook, stirring frequently, until spinach wilts, about 30–60 seconds. Return cooked bacon to the pan if using and combine well.
07 -
Spread vegetables evenly in the pan. Sprinkle grated cheese evenly over the surface and allow to melt slightly.
08 -
Pour egg mixture evenly over vegetables and cheese. Tilt the pan to distribute eggs and cook until edges begin to set, 1–2 minutes.
09 -
Transfer skillet to the oven and bake until eggs are fully set, 8–10 minutes. To test doneness, cut a small slit in the centre; if liquid egg remains, continue baking briefly. For a browned top, broil for 1–2 minutes at the end.
10 -
Let the frittata cool in the pan for 5 minutes. Slice into wedges and serve warm.