This is one of the tastiest ways to cook frozen peas. Make this whenever you want an easy side dish for a meal. I made this with lemon pepper chicken last week and it was the bomb dot com.
Melt the butter in a large skillet over medium-high heat. Add the flour and whisk constantly until it becomes a light golden color, about 2 minutes.
While whisking constantly, pour in the milk. Keep whisking until the mixture thickens, about 1-2 minutes.
Add the peas, salt, and black pepper. Bring to a gentle simmer and cook for 2-3 minutes until the peas are cooked through. If the sauce is too thick, add a little more milk (or water) to thin it out.