Preheat the oven to 400F. Bring water to a boil in a kettle or on the stovetop.
To an 8x8-inch baking dish add the pasta, half & half, butter, Cajun seasoning, salt, and freshly ground black pepper, to taste. Carefully stir in the boiling water. Top with the broccoli florets.
Cover tightly with foil, an oven-safe lid, or an upside-down sheet pan. Bake at 400F for 20 minutes. Check for doneness. The pasta is ready when al dente. If needed, add an extra 5-10 minutes, as I have found that cook time varies based on type of pasta.
Once the pasta is al dente, stir in the cheese and lemon zest. Return to the oven and bake uncovered to melt the cheese completely, another 5 minutes. Remove from the oven and stir. At this point, the pasta is ready.
Optionally, you can add more cheese on top and bake for another 5 minutes, then broil for a minute for a bubbly cheesy topping.
Video
Notes
Half and half: I tested this recipe with half & half and heavy cream. Cream makes the pasta ultra rich and delicious, which half & half creates a cheesy sauce that is on the lighter (but still rich) side. Either works here.
Cheese: I like using "Alpine blend" which is a mix of Swiss and Gruyere cheeses, but shredded Mozzarella or shredded cheddar also work well. I recommend using thick cut cheese over thinly shredded cheese as it tends to melt better.
To double the recipe: Double all ingredients and cook in a 9x13-inch baking dish. Check the pasta for doneness after 25 minutes, adding an additional 10 minutes as needed.
Reheating: Reheats well in the microwave. If reheating in the oven, cover tightly and bake at 325F until heated through, about 20 minutes.