1. Prep: Preheat oven to 400ºF (200ºC) and line two large baking sheets with parchment paper.

2. Toast Seeds: In a dry saucepan, toast the 3 tbsp of sesame seeds over medium-high heat for 3-4 minutes until golden-brown. Set aside to cool completely.

3. Mix Dry Ingredients: In a large bowl, whisk together the gluten-free flour, sugar, baking powder, salt, xanthan gum, garlic powder, paprika, pepper, cooled toasted sesame seeds, and poppy seeds.

4. Cut in Butter: Add the cold, cubed butter to the dry ingredients. Use your fingertips to work the butter into the flour until the mixture resembles coarse breadcrumbs.

5. Form and Rest Dough: Add the cold water and mix with a spatula until a shaggy dough forms. Gently knead it smooth. The dough will be slightly soft and sticky. Let it rest at room temperature for 5-10 minutes.

6. Roll and Cut: Divide the dough in half. On a lightly floured surface, roll out one half very thin, about 1/16 inch (1-2mm) thick. Use a pizza cutter or fluted pastry wheel to cut the dough into individual crackers.

7. Top the Crackers: Transfer the cut crackers to the lined baking sheets. Lightly brush the tops with water. In a small bowl, mix the topping ingredients and sprinkle them over the crackers.

8. Bake: Bake one sheet at a time for 12-14 minutes, or until the crackers are golden brown with slightly darker edges. Let them cool on the baking sheet for a few minutes before transferring to a wire rack to cool completely.