Preheat oven to 375F°. Prepare your potatoes by removing the skin, rinsing and slicing into chunks. Toss potatoes and garlic into a saucepan. Cover with water and bring to a boil. When your water begins boiling, reduce to low/medium heat for 20 minutes or until potatoes are tender.
Meanwhile, brown meat in a large skillet. Part way through, drain of grease and continue cooking. Season your meat as desired. I like to at the very least use a sprinkling of pepper. Stir in flour. Add vegetables, broth and ketchup. Cook for an additional 5 minutes. Transfer to a baking dish of your choosing. I suggest using at least a 2 1/2qt dish.
In a large bowl, toss in sour cream, butter and half of your cheese. When your potatoes are tender, drain and add to bowl. Season with 1 tsp pepper and 1/2 tsp salt. Mash per your liking. I use a potato ricer first as I am not a fan of lumps in my potatoes, followed by an electric mixer.
Top off meat mixture with mashed potatoes. Bake for 18 minutes. Top off with remaining cheese and cook for an additional 2-4 minutes or until cheese is fully melted.
Shepherd's Pie - https://www.bakedbyrachel.com/shepherds-pie/