2. Meanwhile, warm 1 tablespoon of the butter in a medium saucepan over medium-low heat. When the butter starts to bubble, add onion and cook for 3 to 4 minutes, until translucent, stirring often.
3. Add the peas and water to the pan and cook 3 minutes, stirring. Stir in the ham and cook 2 minutes. Add the cream; bring to a low simmer and cook 5 minutes.
4. Drain pasta; place in large serving bowl. Stir remaining 2 tablespoons butter into the cream mixture over low heat until melted. Stir in the cheese. Pour sauce over pasta and toss to coat. Season with salt and pepper to taste.
