Preheat a smoker to 275°F. Lightly grease a small loaf pan with the neutral oil.
In a large bowl, combine the ground turkey, egg, breadcrumbs, onion, garlic powder, smoked paprika, salt, black pepper, and 1/4 cup milk. Mix gently just until combined. Press the mixture evenly into the prepared loaf pan.
In a separate bowl, whisk together the cornmeal, flour, baking powder, and brown sugar. Stir in the shredded cheddar and diced jalapeño. In another bowl, whisk the second egg with the 1/3 cup milk and melted butter. Add the wet mixture to the dry ingredients and stir until just combined.
Spread the cornbread batter evenly over the turkey mixture, reaching the edges of the pan to form a crust.
Place the pan in the smoker and cook until the center of the meatloaf reaches 165°F, checking with an instant-read thermometer. The cornbread crust should be set and lightly golden.
Remove the pan from the smoker and let the meatloaf rest for 10 minutes. Slice carefully so each piece keeps its layer of jalapeño-cheddar cornbread crust.