Step 1

Heat the oil in a heavy-bottomed 10- or 12-inch skillet over medium heat until shimmering. Add the tomatoes, salt, black pepper, and red pepper flakes, if using. Cook until the tomatoes soften and release their juices, 5 to 6 minutes. Stir in the garlic and cook until fragrant, about 1 minute.

Step 2

Increase the heat to medium-high, stir in the tortellini, and cook, stirring occasionally, until the tortellini is plump and tender, 3 to 5 minutes, or according to package instructions.

Step 3

Remove from the heat and stir in the spinach until it just wilts, about 1 minute. Serve immediately with plenty of grated Parmesan cheese.