Knead the ground turkey together with the onion and season with salt and pepper.
Mix the cream cheese, jalapeño, cheddar, and one finely chopped garlic clove into a creamy mixture.
For each burger, press around an eighth of the meat into a round patty. Place a quarter of the cream cheese mix on top and cover the filling with another eighth of the meat.
Close the edges of the jalapeño burgers and fry each burger in hot oil until both sides are brown.
To serve, place your filled turkey burger in a bun with the toppings and sauce of your choice.