Sour Cream Enchilada Casserole

My mom has made this recipe for years, and my brother and I love it. It's my brother's favorite recipe.

Sour Cream Enchilada Casserole
Southern Living, 1982 Annual Recipes
Serves 8

Ingredients
1 cup water
1/4 cup plus 2 Tbsp picante sauce, divided
12 corn or flour tortillas
2 lbs ground beef
1 onion, chopped
1 to 1-1/2 tsp salt
1/8 tsp pepper
2 tsp ground cumin
1 Tbsp chili powder
1 tsp garlic powder
3/4 cup ripe olives, sliced (optional)
1/2 cup butter or margarine (my mom uses 1/4 cup smart balance)
2 Tbsp all-purpose flour
1-1/2 cups milk
1 (16-oz) carton commercial sour cream (can use low fat)
2 cups (8-oz) shredded Cheddar cheese

Directions
Combine water and 2 Tbsp picante sauce in a large shallow dish. Place tortillas in picante sauce mixture; let stand 5 minutes. Drain.

Cook ground beef (or ground turkey) and onion in a heavy skillet until brown; drain off drippings. Stir in salt, pepper, cumin, chili powder, garlic powder, olives (optional), and 1/4 cup picante sauce; simmer meat mixture 5 minutes.

Melt butter in a heavy saucepan over low heat; add flour, stirring until smooth. Cook 1 minute, stirring constantly. Gradually stir in milk; cook over medium heat, stirring constantly, until thickened and bubbly. Remove from heat, and add sour cream; stir until well blended.

Place half of tortillas in a 9x13x2 inch baking dish. Pour half of sour cream sauce over tortillas; spoon half of meat mixture evenly over sauce. Sprinkle half of cheese mixture over meat mixture. Repeat layers with remaining ingredients. Bake at 375 degrees for 25 minutes.