Mashed Potatoes with Blue Cheese and Port-Caramelized Onions

Recipe from Cook's Illustrated

Onions

1 ½ teaspoons unsalted butter

1 ½ teaspoons vegetable oil

¼ teaspoon salt

½ teaspoon light brown sugar

1 pound yellow onions (4 small or 3 medium) sliced ¼ inch thick

1/3 cup port, preferable ruby port

Potatoes

¾ cup half-and-half

1 teaspoon chopped fresh thyme leaves

2 pounds russet potatoes, unpeeled and scrubbed

6 tablespoons unsalted butter, melted

1 ¼ teaspoons salt

½ teaspoon ground black pepper

4 ounces blue cheese, crumbled

FOR ONIONS: Heat butter and oil in 8-inch nonstick skillet over high heat; when foam subsides, stir in salt and sugar. Add onions and stir to coat; cook, stirring occasionally, until onions begin to soften and release some moisture, about 5 minutes. Reduce heat to medium; cook, stirring frequently, until onions are deeply browned and sticky, about 35 minutes longer (if onions are sizzling or scorching, reduce heat; if onions are not browning after 15 minutes, increase heat) Stir in port; continue to cook until port reduces to glaze, 4-6 minutes. Set onions aside.

FOR POTATOES: While onions are cooking, bring half-and-half and thyme to boil in small saucepan or microwave oven; cover to keep warm. Follow recipe for Mashed Potatoes with Scallions and Horseradish through step 2.

Stir butter into potatoes until just incorporated. Sprinkle with salt and pepper. Add warm half-and-half and cheese; stir until just combined. Serve immediately, topped with onions.