Follow the instructions on the bag to cook the frozen peas. I always do mine in the microwave. Drain well.
Over medium heat, melt the butter. Add flour, salt, black pepper, garlic powder, and sugar - stir until well-combined. Slowly add the whole milk, whisking continuously. Bring sauce to a boil, whisking until it has thickened. This should take about 2 minutes.
Add the peas to the cream sauce, mix well, and allow the peas to warm. Serve and enjoy!