Preheat oven to 400 degrees F.
If using a head of cauliflower, wash and cut florets off. Place florets into a microwave safe bowl. Add 2-3 tablespoons of water, cover with a paper towel and microwave for 4-5 minutes and allow to steam for 2 minutes.
Remove from microwave and drain in a colander placed over a large pot or in the sink. (be careful, steam will be hot.)
Transfer cooked cauliflower back into a large bowl. Add garlic powder, salt, softened cream cheese and butter. Stir to combine.
Using a food processor with the standard blade attachment OR an immersion blender, puree mixture until smooth.
Spoon half of the cauliflower mixture into a baking dish. Top with half the asiago cheese. Add the remaining cauliflower mixture and top with the remaining asiago cheese.
Bake for 30 minutes or until golden, bubbly, and hot. Season with salt and pepper to taste and serve immediately.
Leftovers can be refrigerated in an airtight container for up to 3 days, but will need to be reheated in the microwave on 50% power until hot throughout.