Melt the butter in a 12-inch skillet over medium heat.
Add the cubed chicken and cook, stirring occasionally, until browned and cooked through, about 8 minutes; transfer the chicken to a bowl and set aside.
Prepare the roasted red pepper cream sauce in the same skillet according to its recipe.
Drain the cooked pasta and add it to the skillet with the cream sauce; toss with tongs to coat evenly.
Add the cooked chicken back to the skillet, then add the fresh spinach and remove from heat; toss until the spinach wilts.
Season with salt and pepper to taste and serve warm.