Preheat oven to 425 degrees F (218 degrees C)
Chop potatoes into 1.5-inch sections. Try to keep them all the same size so they cook evenly. Dry very well with a paper towel (very important step)
In a large bowl, add chopped potatoes, 2 tablespoons olive oil (reserve 1 tablespoon of olive oil for shrimp and peppers) onions, 1 tsp garlic powder, 1 tsp paprika, 1 tsp cumin powder, salt and pepper and toss well. (reserve the other teaspoons of garlic powder, paprika and cumin powder for the shrimp and peppers) You can also do this step right on the baking sheet pan, if you do not want to dirty another bowl.
Place seasoned potatoes and onion on a lined sheet pan in a single layer. (line your baking sheet with aluminum foil and you can thank us later as clean-up is a snap) Make sure there is no overlapping of potatoes.
Bake potatoes and onions for 20 minutes and then toss. Place back in the oven to continue baking.
In the meantime, Unthaw, peel and devein shrimp and remove tail. Dry well. Set aside. Chop your bell peppers.
Toss your shrimp, bell peppers, 1 tablespoon olive oil, 1 teaspoon of garlic powder, 1 teaspoon of paprika, 1 teaspoon of cumin, salt and pepper together. At the 24 minute mark of baking, add your seasoned shrimp and bell pepper mixture to the roasted potatoes, toss and spread out in an even layer to continue roasting for 6-8 minutes or until the shrimp are no longer translucent.
Test to make sure your potatoes are fork tender and your shrimp are no longer translucent. Your shrimp should be nice and pink. Remove from the oven. Enjoy!