Preheat the oven to 350°F. Line a baking sheet with parchment paper and set aside.
In a large bowl, whisk together the flour, baking powder, and salt. Add the yogurt and stir everything together with a rubber spatula until a shaggy, crumbly dough forms.
Using your hands, knead the dough until smooth, around 2 minutes. It will look dry at first but should come together into a craggy, slightly tacky mass similar to biscuit dough.
Divide the dough into 4 to 6 equal pieces and roll each into a smooth ball. Lightly flour your hands, then use your finger to poke a hole in the center of each bagel. Gently roll and stretch the dough until the center is around 1 inch in diameter and 1 inch tall. Repeat with the remaining pieces of dough, adding flour if needed.
Arrange the bagels onto the prepared baking sheet. To make the egg wash, beat the egg with 1 tablespoon of water or milk. Brush the bagels with the egg wash and sprinkle with toppings of choice.
Bake the bagels for around 30 minutes or until lightly golden and cooked through—they will not take on much color after baking, but this is normal. Let the bagels cool for at least 15 minutes before slicing, toasting, and serving.