Gluten Free Blueberry Streusel Muffins

Name: Gluten Free Blueberry Streusel Muffins
Cuisine: European
Ingredients: 90 g (¾ cup) plain gluten free flour blend (I used Doves Farm Freee gluten free plain white flour that doesn't have any xanthan gum added. You can also mix your own gluten free flour blend using this recipe. Note that for this homemade blend, 1 cup = 150g, so ideally use a digital food scale and the weight measurements for best results.); ▢50 g (¼ cup) light brown soft sugar; ▢¼ tsp xanthan gum (Omit if your gluten free flour blend already contains xanthan gum.); ▢45 g (3 tbsp) cold unsalted butter, cubed; 150 g (¾ cup) caster/superfine or granulated sugar; ▢zest of 1 lemon (Ideally, use organic unwaxed lemons.); ▢85 g (¾ stick) unsalted butter, melted and cooled until warm; 75 g (⅓ cup) full-fat Greek-style yoghurt, room temperature; ▢2 US large/UK medium eggs, room temperature; ▢½ tsp vanilla bean paste (or 1 tsp vanilla extract); ▢240 g (2 cups) plain gluten free flour blend (I used Doves Farm Freee gluten free plain white flour that doesn't have any xanthan gum added. You can also mix your own gluten free flour blend using this recipe. Note that for this homemade blend, 1 cup = 150g, so ideally use a digital food scale and the weight measurements for best results.); ▢1¼ tsp baking powder; ▢½ tsp baking soda; ▢½ tsp xanthan gum (Omit if your gluten free flour blend already contains xanthan gum.); ▢¼ tsp salt; ▢280 g (about 2 cups) fresh blueberries (You can reduce the amount to 210g/1½ cups if you prefer less fruit in your muffins.)