Cheese Onions Recipe

Slice onions

Peel and thinly slice enough yellow onions to yield about 2 cups (about 2 medium onions). Keep slices even so they cook uniformly.

In a large skillet over medium heat, add 1 tbs olive oil and 1 tbs unsalted butter. When butter melts and begins to foam, add the sliced onions and spread them into an even layer.

Season onions with 1 tsp salt, 1 tsp black pepper, and 1 tsp granulated sugar. Stir to combine, then reduce heat to medium-low.

Cook, stirring every 3–5 minutes, until onions are deeply softened and lightly caramelized, about 20–25 minutes. If they begin to stick, add 1–2 tbs water and scrape browned bits from the pan. Stir in 1 tbs fresh thyme leaves during the last 2 minutes of cooking.

Once onions are caramelized, push them to one side of the pan. Add the remaining 1 tbs butter and 1 tbs flour to the empty side and cook the roux for 1 minute, stirring to remove the raw flour taste.

Slowly whisk in 120 ml milk and 60 ml heavy cream, bringing the mixture to a gentle simmer. Stir continuously until the sauce thickens slightly, about 2–3 minutes.

Reduce heat to low and gradually add 1.5 cups grated sharp cheddar, 0.5 cup grated gruyere, and 0.25 cup grated parmesan, stirring until cheese melts and the sauce is smooth and glossy. Taste and adjust seasoning with a pinch more salt or pepper if needed.

Fold the caramelized onions into the cheese sauce until evenly combined and heated through, about 1–2 minutes. If the sauce is too thick, stir in up to 2 tbs milk to reach desired consistency.

Transfer the cheese onions to a serving bowl. Sprinkle with 1 tbs chopped chives and 1/4 tsp cracked black pepper, if using.

Serve warm with toasted baguette slices or crackers (about 12 pieces) for dipping. Leftovers can be stored in an airtight container in the refrigerator for up to 3 days; gently reheat on low and add a splash of milk if needed to loosen the sauce.