Preheat oven to 375°F (190°C).

In a medium pan, heat olive oil over low heat. Add white onion and garlic and sauté until soft, about 2-3 minutes.

Add chopped green chiles, Navy beans, water, chicken bullion, and cumin. Mix well, cover, and simmer on low for 15 minutes.

Remove the cover, add shredded chicken, and cook for an additional 5 minutes, or until the mixture thickens and the liquid boils down. Set aside.

In a large nonstick pan, melt the butter over medium heat. Add chopped white onion and cook, stirring occasionally, until softened and slightly translucent, about 3-4 minutes.

Add flour and stir well. Cook for 1 minute, stirring constantly. Slowly whisk in the chicken broth until the sauce becomes smooth.

Cook over medium heat until the sauce boils and thickens, about 4-5 minutes. Stir in the chopped green chiles, jalapeños, and salt to taste.

Cook for another minute, then remove from heat. Stir in the light sour cream.

Spread about 1/4 cup of the salsa verde sauce on the bottom of a 9x13 inch baking dish. Fill each tortilla with 1/3 cup of the chicken and white bean filling.

Roll the tortillas and place them seam-side down in the prepared baking dish. Continue filling and rolling the remaining tortillas.

Pour the remaining salsa verde sauce over the top of the enchiladas. Sprinkle with shredded Mexican cheese.

Cover with aluminum foil and bake for 20-30 minutes, until the enchiladas are hot and the cheese is melted. Remove from oven and garnish with fresh cilantro or scallions.