Preheat oven to 375°F. Place rack in the middle position. Lightly grease an 8x8 baking dish or pie plate.
In a large bowl, stir together whipped cream cheese, mayo, sour cream, and ranch seasoning until smooth.
Mix in mozzarella, ¾ of the Colby Jack, fresh jalapeños, diced jarred jalapeños, most of the bacon, and green onions.
Spread evenly into the prepared dish.
Garnish before baking: layer the 6 whole jalapeño slices on top, then sprinkle with the reserved Colby Jack, bacon bits, and green onions (down the center).
Bake uncovered for 20–25 minutes, until hot, melty, and bubbling around the edges.
Serve immediately with tortilla chips, crackers, or baguette slices.