In a medium saucepan, melt butter over medium heat. Whisk in the flour to create a roux and cook for 1-2 minutes, stirring constantly.
Gradually add the chicken broth, whisking to avoid lumps, and bring the mixture to a simmer. Cook for about 3-5 minutes until it starts to thicken.
Reduce the heat to low and stir in the sour cream and cream cheese. Whisk until the cream cheese melts and the sauce is smooth.
Stir in the shredded cheese, garlic powder (if using), salt, and pepper. Cook for an additional 2-3 minutes until the sauce is thickened and cheesy. Remove from heat.
3. Assemble the Enchiladas:
