Method
1. Cook the Bacon
Preheat the oven to 350°F and grease a 9x13-inch baking dish. Cook the bacon in a large skillet over medium heat, turning occasionally, until crisp, 8-10 minutes. Transfer to a paper-towel-lined plate and pour off all but 1 tablespoon of fat.
2. Scramble the Eggs
Whisk the eggs and milk together until light and frothy. Pour into the same skillet and cook over medium-low heat, stirring often, until just barely set, 2-3 minutes. Season with salt and pepper and stir in the chives, then remove from the heat immediately—the eggs will keep cooking in the residual heat.
3. Build the Sliders
Spread the cream cheese over the bottom halves of the bagels and arrange side by side in the prepared dish. Layer with the scrambled eggs, crumbled bacon, and cheddar, then close with the top halves.
4. Butter and Bake
Brush the tops with melted butter and sprinkle with the dried onion, garlic, poppy seeds, and sesame seeds. Bake until the bagels are toasted and the cheese has melted, about 10 minutes. Serve warm.