In a mixing bowl, combine the shredded cheddar cheese, shredded pepper jack cheese, cream cheese, chopped jalapeños, and chopped green onions. Mix until well combined. Set aside.
In a separate bowl, whisk together the flour, cornmeal, baking powder, garlic powder, salt, and black pepper.
In another bowl, mix the buttermilk and the egg until well incorporated.
Gradually add the wet ingredients to the dry ingredients, stirring until just combined. The batter should be thick.
Add the cheese and jalapeño mixture to the batter and fold gently until evenly distributed.
Heat oil in a frying pan or deep fryer to 350°F (175°C).
Using a spoon or cookie scoop, drop balls of the mixture into the hot oil. Fry in batches to avoid overcrowding the pan.
Cook for about 3-4 minutes or until golden brown and crispy. Use a thermometer to ensure the oil stays at the correct temperature.
Once cooked, remove from the oil and drain on paper towels.
Serve warm with ranch dressing on the side for dipping.