Preheat your oven to 350°F (175°C). Lightly grease and flour a 9x5 inch loaf pan, then line it with parchment paper.
In a spacious bowl, gently sift your flour and baking powder. Stir in the sugar, salt, onion powder, both cheeses, and the diced jalapeño.
In a separate, smaller bowl, simply whisk together your eggs and milk until they're well combined.
Gradually pour the egg and milk mixture into your dry ingredients. Add the melted butter and mix just until everything comes together. Avoid over-mixing.
Spoon the batter evenly into your prepared loaf pan. You can press a few extra jalapeño slices on top before baking.
Bake for 60 to 80 minutes. The bread is done when a toothpick inserted into the center comes out clean. If the top browns too quickly, cover it with aluminum foil.
Let your bread cool in the pan for 10 minutes, then transfer it to a wire rack to cool completely.
Notes
Nutritional Information (per serving): Calories: 213, Total Carbs: 19g, Net Carbs: 18g, Fats: 12g, Protein: 6g