In a medium mixing bowl, combine the cooked cubed chicken, drained black beans, drained corn, chopped red bell pepper, sliced green onions, seeded and chopped jalapeños, and chopped spinach.
Add the chili powder, cumin, garlic powder, salt, pepper, and shredded Monterey Jack cheese to the bowl; stir until evenly combined.
Place one egg roll wrapper on a clean surface as a diamond. Spoon about 2 tablespoons of the filling into the center of the wrapper.
Wet the wrapper edges with a little water, fold the bottom corner up over the filling, fold in both side corners, then roll tightly to seal. Repeat with remaining wrappers and filling.
Pour oil into a large skillet to about 1 inch depth and heat over medium-high until shimmering. Fry egg rolls in batches for 1–2 minutes per side until golden brown and crispy.
Drain cooked egg rolls on paper towels briefly and serve hot with cilantro ranch dressing for dipping.