How to Make It
Preheat broiler with oven rack 6 inches from heat. Thinly slice garlic cloves, and chop spinach. Cook garlic in 1/2 tsp. olive oil in a skillet over medium, stirring often, until softened and lightly golden, about 2 to 3 minutes. Add spinach, and cook, stirring occasionally, until wilted, about 1 minute. Remove spinach mixture from heat, and set aside. Cut potato in half, and scoop out pulp into a bowl, leaving 1/4-inch-thick shells. Mash pulp with warm milk, 2 1/2 tsp. olive oil, salt, and pepper until mostly smooth. Fold in spinach mixture. Spoon into shells, and place on a baking sheet. Top evenly with feta cheese. Broil until lightly browned and warmed through, 2 to 3 minutes. Sprinkle evenly with dill and lemon zest.