Makes 4 servings
In a medium-large skillet over medium heat, warm the olive oil. Add the pancetta and sautè until it becomes crispy, stirring to avoid burning.
Add the leak and the potatoes, and cook until firm but soft enough to put a form through. Stir in the thyme. Add the peas and cook, stirring occasionally, for 5 to 6 minutes. Season with salt and pepper to taste. Turn off the heat, but leave the pan on the burner.
Meanwhile, in a large pot of boiled salted water, cook the penne until al dente, drain and transfer to the skillet. Add the Parmigiano and quickly sautè adding pasta water as necessary to bind the ingredients.
Plate in four bowls. Finish with a spoonful of crème fraîche, a drizzle of oil, more pepper, and a thyme sprig for decoration.