This oven baked 4-ingredient potatoes O’Brien is the kind of simple, cozy side dish that shows up in old church cookbooks and family potlucks all over the Midwest. My uncle requested this every single Sunday dinner when I was growing up, and my aunt swore she first copied it from a yellowed church cookbook page taped inside her cabinet door. It’s just diced potatoes, bell peppers, onion, and butter, baked until the edges are crispy and the peppers are soft and sweet. No fuss, no fancy steps—just a pan of golden, colorful potatoes that you can slide into the oven while you finish the rest of dinner.
Serve these potatoes O’Brien straight from the glass baking dish with roasted chicken, meatloaf, ham, or a simple pan-fried pork chop—exactly how they’d show up at those church basement suppers. They’re also perfect for brunch alongside scrambled eggs, sausage, or a breakfast casserole. Add a dollop of sour cream or a drizzle of ketchup or hot sauce at the table if your crew likes condiments. Leftovers reheat well in a skillet with a little extra butter or oil and pair nicely with a green salad or steamed veggies for a quick, no-stress weeknight plate.
Oven Baked 4-Ingredient Potatoes O'BrienServings: 6
Ingredients
2 1/2 pounds russet or Yukon gold potatoes, scrubbed and diced into 1/2-inch cubes
1 large onion (yellow or white), diced
2 medium bell peppers (any colors, such as red and green), diced
1/3 cup unsalted butter, melted, plus more for greasing the dish
1 teaspoon kosher salt (or to taste)
1/2 teaspoon black pepper (or to taste
Optional: 1/2 teaspoon garlic powder or paprika, for a little extra flavor
Directions
Preheat your oven to 400°F (200°C). Lightly butter a 9x13-inch glass baking dish so the potatoes don’t stick and you get those nice crispy edges.
Prep the vegetables: Scrub the potatoes well and cut them into 1/2-inch dice so they cook evenly. Dice the onion and bell peppers into similar-size pieces. Keeping everything roughly the same size helps the potatoes and veggies cook through at the same time.
Add the diced potatoes, onion, and bell peppers to the prepared glass baking dish. Spread them out into an even layer as much as possible; this helps them brown instead of steam.
In a small bowl or measuring cup, melt the butter in the microwave or on the stovetop. Stir in the salt, black pepper, and, if using, garlic powder or paprika. Drizzle the seasoned melted butter evenly over the potato mixture in the baking dish.
Use a spatula or clean hands to toss everything right in the baking dish until the potatoes, onions, and peppers are well coated in the butter and seasoning. Pat the mixture back into an even layer so the top can brown in the oven.
Bake uncovered for 25 minutes. Carefully remove the dish from the oven and give the potatoes a good stir, scraping up any browned bits from the bottom and corners of the glass dish.
Return the dish to the oven and continue baking for another 20–25 minutes, stirring once more if needed, until the potatoes are tender when pierced with a fork and the edges are golden and crispy. Total bake time is usually 45–50 minutes, depending on your oven and how crowded the pan is.
Taste and adjust seasoning with a little more salt and pepper if needed. Serve the potatoes O’Brien hot, right in the glass dish, for that nostalgic, church-supper feel. They’ll stay warm on the table for a while, and the edges will keep getting a little extra crispy as they sit.
Variations & Tips
For a make-ahead option, you can dice the potatoes, onion, and peppers up to a day in advance and store them (separately or together) in airtight containers in the fridge. If you prep the potatoes ahead, place them in cold water in the fridge to prevent browning, then drain and pat very dry before baking so they crisp instead of steam. For a slightly lighter version, swap half the butter for olive oil. To make it more like a full brunch dish, stir in 1 cup of diced cooked ham or cooked breakfast sausage before baking; just be sure the meat is fully cooked and cooled before adding. If you want extra color and flavor, use a mix of red, yellow, and green peppers, or sprinkle on a teaspoon of dried parsley or Italian seasoning with the butter. For crispier potatoes, spread everything into two baking dishes so they’re in a thinner layer, and bake on the top and middle racks, rotating halfway through. Food safety tips: Always wash potatoes and vegetables well before cutting. If you add any meat, make sure it’s cooked to a safe internal temperature before mixing in (165°F for poultry, 160°F for ground meats). Refrigerate leftovers within 2 hours in a shallow container and reheat thoroughly in a hot skillet or 350°F oven until steaming in the center before serving.
