Preparation

• Melt the butter and oil in a 12-inch skillet over medium heat. Add the chard stems and cook until starting to soften, about 1 minute. Add the chard leaves by the handful 1 and cook, stirring, until wilted and all of the liquid has cooked off, 4 to 5 minutes. Season to taste with salt and pepper, and set aside.

• In a 2-quart saucepan, combine 3 Tbs. of the lemon juice with the sour cream, mustard, 1/4 tsp. salt, and 1/4 tsp. pepper. Whisk over medium-low heat until heated through, about 1 minute. Keep warm.
• In a 3-quart straight-sided sauté pan, bring 1 inch of water and 1 Tbs. of the lemon juice to a slow simmer. Crack the eggs one at a time into a small bowl and then gently slide each egg into the water. Poach the slotted spoon, blot gently with a paper towel, and set aside.
• Position a rack 5 to 6 inches from the broiler and heat the broiler on high. Place the bread on a baking sheet and toast under the broiler until golden on both sides, 1 to 2 minutes per side. Divide the chard among the slices. Top each one with an egg and two slices of the cheese. Broil until the cheese melts, about 1-1/2 minutes. Transfer to plates, and top with some of the sauce. Serve with the remaining sauce on the side.