My sister showed me this 4 ingredient dinner and it has been a springtime staple for us ever since.

To keep this aligned with the spirit of a 4-ingredient dinner, think of any additions as optional flourishes rather than requirements. For extra savoriness, you can whisk 1/2 cup of finely grated Parmesan into the cream before pouring it over the tortellini. If you prefer a lighter sauce, replace up to 1/2 cup of the heavy cream with whole milk, understanding the sauce will be slightly thinner and less rich. Fresh peas can be used in place of frozen when they’re in season; blanch them for 1–2 minutes in boiling water, then drain and cool before adding so they keep their bright color. If you don’t have diced ham, chopped leftover holiday ham, smoked turkey, or even Canadian bacon will work; just be sure it’s fully cooked before it goes into the casserole. For a subtle kick, add a pinch of crushed red pepper flakes or a small grating of nutmeg to the cream mixture. Food safety tips: Use only fully cooked ham and keep it refrigerated until you assemble the dish. If using leftover ham, make sure it hasn’t been at room temperature for more than 2 hours total since it was first cooked. Bake the casserole until it is visibly bubbling and the center is piping hot; a food thermometer inserted into the middle should read at least 165°F (74°C). Refrigerate leftovers within 2 hours of baking and reheat thoroughly before eating, adding a splash of cream or milk if the pasta seems dry.