In a skillet over medium heat, add bacon. Cook to your desired crispness.
When the bacon is done, remove to a plate lined with a paper towel. Set aside.
Add the onion to the skillet. Cook until translucent. Remove to a small bowl and set aside.
Add the mushrooms. Cook until softened. Drain and remove to a small bowl and set aside.
Preheat your oven to 425 degrees.
Add the frozen hash browns to a large bowl. Season with your favorite seasonings. I use salt, pepper, granulated garlic, and Mrs. Dash.
Add in the olive oil. Stir until the hash browns are coated with oil and seasonings.
Line a sheet pan with parchment paper. Spray with olive oil spray.
Spread out the frozen hash browns on the sheet pan.
Put the hash browns in the oven the lower center rack. Bake for approximately 30 minutes. If you want it to be crispy, raise the rack one level. Watch it very closely and brown for about 5 more minutes. Add cheddar cheese and allow to melt, if desired.
Remove the hash browns from the oven.
Top the hash browns with bacon, onions, mushrooms, and tomatoes.