Preheat the oven to 400 degrees . Line a 12-cup muffin pan with 1 1/4-inch paper liners. In a bowl, whisk the flour, baking powder, caraway seeds, garlic, onion, poppy seeds, sesame seeds and salt. In a large bowl, whisk the buttermilk, oil and eggs. Add the dry ingredients to the wet mixture and fold until just barely blended.
Whisk together first 4 topping ingredients.
Divide the batter among the liners (fill about three-quarters). Brush muffin tops with beaten egg and sprinkle with topping mixture. Bake until puffed and golden brown and a toothpick inserted into the center comes out clean, 13 to 17 minutes. Cool in the pan.
