Preheat your oven to 400°F (200°C). Line a 12-cup muffin tin with paper liners.
In a large bowl, whisk together the gluten-free flour blend, baking soda, cinnamon, nutmeg, allspice, and salt.
In a separate medium bowl, whisk the granulated sugar, brown sugar, egg, milk, melted butter, and vanilla extract until combined.
Pour the wet ingredients into the dry ingredients. Mix gently with a spatula until just combined; do not overmix.
Fold in the dried fruit and candied peel, if using.
Divide the batter evenly among the 12 muffin cups, filling each about two-thirds full.
Bake for 18 to 20 minutes, or until a toothpick inserted into the center comes out clean.
Let the muffins cool in the tin for 5 minutes before transferring them to a wire rack to cool completely.
While the muffins cool, prepare the cross topping. Whisk together the powdered sugar, 1 tablespoon of milk, and lemon juice until smooth.
Transfer the glaze to a small piping bag or a small zip-top bag with a tiny corner snipped off. Pipe a straight line across the top of each cooled muffin to form a cross shape. Let the glaze set before serving.
Notes
If your gluten-free flour blend does not contain xanthan gum, add 1 teaspoon to the dry ingredients for structure.
For a dairy-free option, use almond or soy milk and substitute the butter with a neutral oil like canola or vegetable oil.
You can substitute the lemon glaze cross with a simple water-based icing if you prefer a sweeter finish.