Combine a cup of chilled Salsa Huancaina, one egg, and a cup of milk in a large mixing bowl. Stir to blend, but don't whip too vigorously. You don't want to incorporate too much air into the mixture.
In a separate bowl, mix the masa harina, AP flour, baking powder, and salt.
While gently stirring the cheese, egg, and cheese mixture, slowly add all of the dry ingredients to the bowl. Adding the dry ingredients to the wet ones will help to eliminate any lumps from forming.
Thin out the batter by adding more milk while continuously stirring until you reach the consistency of a thick pancake batter.
Let the batter rest in the fridge for about 15 minutes to ensure all the dry ingredients are thoroughly hydrated. The batter usually tightens up a little while resting, so you will need to add a little more milk.
Heat a griddle or a pan with a heavy bottom over medium heat for about 5 - 10 minutes. Ideally, you want a surface temperature of around 350 degrees. You can test to see if the surface is how enough by dropping water on the surface. If it sits there and steams, it's too cold, but if it immediately disappears, it's too hot. You will know the surface is at the perfect temperature for cooking when the water "dances" around before disappearing.
Spray the cooking surface with cooking spray.
Pour a 1/4 cup of pancake batter onto the cooking surface. You can cook multiple pancakes at once, but make sure there is at least a quarter-inch of space between each pancake.
Don't touch the pancake for two to three minutes. You should see tiny bubbles popping on the pancakes, and the edges will begin to dry out.
Flip the pancakes and cook for an additional two to three minutes.
Keep warm, covered with tin foil in an oven set on low, or serve immediately.