Place defrosted hash browns in large bowl with minced onions and microwave on high for 5 minutes (if potatoes are still frozen, microwave for 10 minutes).
Bring water to boil with chicken cube. Add to potatoes and mix well. Let sit for at least 5 minutes.
Place half and half, cheese spread, and garlic pepper in small bowl, microwave for 1 minute, mix well. Add to potatoes with cubed velveeta cheese. Mix well.
Place potatoes in two 8x8 buttered casserole dishes. Cover dishes with plastic wrap venting one side. Microwave each dish on high for 10 minutes. Let potatoes sit for an additional 10 minutes.
Mix cheddar cheese and shredded velveeta cheese together.
Top potatoes with shredded cheese, microwave each for 5 minutes, covering dishes with plastic wrap, vent one side. Or cover with foil and place both dishes in oven at 350 degrees for 15 minutes (I use this second method if oven is already on and being used for other foods).
Test for doneness (potatoes should be soft), return to oven if neccessary.