Preheat the oven to 350°F (175°C).
Reserve a portion of the cooked bacon, 1/4 cup Parmesan, 1/4 cup sharp cheddar, a small amount of diced jalapeños, and one sliced green onion for garnishing.
In a large mixing bowl, combine the remaining chopped bacon, softened cream cheese, sour cream, mayonnaise, 1/2 cup sharp cheddar, 1/4 cup Parmesan, garlic powder, two sliced green onions, and the finely diced jalapeños. Mix thoroughly until smooth and fully incorporated.
Transfer the dip mixture into a 1.5-quart (1.5-liter) baking dish, smoothing out the surface evenly.
Scatter the reserved bacon, jalapeños, green onion, Parmesan, and cheddar evenly over the top.
Bake for 20 to 25 minutes, or until the surface is golden and bubbling.
Serve warm with celery sticks, low-carb crackers, or your preferred accompaniments.