How to Make It
Preheat oven to 425°F with oven rack in lower third of oven. Cook chopped bacon in a medium nonstick skillet over medium-high, stirring occasionally, until crisp and golden, 5 to 7 minutes. Using a slotted spoon, transfer to a plate lined with paper towels. Allow drippings to cool slightly in skillet, about 5 minutes; pour into a small heatproof bowl.
Add 2 tablespoons melted butter to drippings; stir to combine. Spoon 1 teaspoon drippings mixture into each cup of a 12-cup popover pan or large muffin pan. (Discard any remaining drippings mixture.) Place pan in oven to heat.
Stir together flour and salt in a medium bowl. Whisk together milk, maple syrup, eggs, and remaining 2 tablespoons butter in a large bowl. Gradually whisk flour mixture into egg mixture until almost smooth; fold in cooked bacon. Transfer batter to a 4-cup spouted measuring cup.
Carefully remove hot pan from oven. Pour batter into popover cups, filling each two-thirds full. Bake in preheated oven until popovers are puffed and golden brown, 18 to 20 minutes. Lightly brush tops with additional maple syrup. Remove from pan, and serve immediately.