Preheat your oven to 375°F (190°C). Line a baking sheet with parchment paper.
In a medium bowl, combine spinach, artichoke hearts, cream cheese, sour cream, minced garlic, salt, pepper, and red pepper flakes (if using). Mix until well combined.
Place the bagel halves on the prepared baking sheet, cut side up. Brush the tops lightly with olive oil.
Evenly spreading the spinach-artichoke mixture over each bagel half.
Sprinkle the mozzarella and Parmesan cheese over the top.
Bake for 12-15 minutes, or until the cheese is melted and bubbly and the bagels are slightly crisp. Sprinkle with poppy seeds (if using).
Let them cool slightly before serving. Enjoy warm!