Preheat oven to 375°F. Line a baking sheet with parchment paper and set aside.

In a large bowl, whisk together together the flour, sugar, baking powder, baking soda and salt. Add in the butter and rub with your fingers until the mixture resembles coarse crumbs. Stir in the smoked salmon, 2 tablespoons of the bagel seasoning, and scallions until evenly combined. Add the buttermilk and stir with a wooden spoon or rubber spatula until it comes together to form a rough dough.

Transfer to a lightly floured work surface, knead a few times and divide into eight even pieces. Gently form each into rounds and place on the prepared baking sheet, spacing them out evenly. Using a sharp knife, score an X on the top of each. Sprinkle each with the remaining bagel seasoning. Bake until golden brown, about 20 to 22 minutes.