Add the broccoli to a pot of boiling water, and blanche until just becoming tender. Remove, and immediately place in an ice bath or run under cold water to stop the cooking. Drain and set aside.
Preheat the oven to 375 degrees.
Melt the butter in a pot over medium heat.
Add in the onions, and saute until softened.
Stir in the garlic, and saute another 30 seconds.
Mix in the cream cheese until completely melted.
Slowly whisk in the heavy whipping cream until well combined.
Stir in the cheddar and colby jack cheeses until melted.
Pour the cheese sauce over the broccoli in a large mixing bowl, and stir to combine.
Spread the mixture into a well greased 9x9 baking dish.
Combine the pork rind crumbs and parmesan cheese in a bowl.
Sprinkle the crumb mixture over the mac and cheese.
Bake for 25 minutes.