In a large mixing bowl, combine cooked shredded chicken, shredded cheddar cheese, and softened cream cheese. Stir in sour cream until smooth. Add garlic powder, onion powder, cumin, chili powder, and salt and pepper to taste. Mix thoroughly.

Lay a flour tortilla flat, spoon 2-3 tablespoons of the chicken mixture onto the bottom third, and roll tightly. Place seam-side down on a tray. Repeat with remaining tortillas and filling.

Heat 1 inch of vegetable oil in a skillet over medium-high heat until it reaches 350°F to 375°F. Test readiness by dipping the edge of a tortilla in the oil.

Add taquitos to the hot oil seam-side down, frying in batches to avoid overcrowding for 2-3 minutes until golden brown. Turn and fry for another 2-3 minutes.

Remove taquitos from skillet and place on a paper towel-lined plate to drain excess oil. Serve warm with optional toppings.