Preheat your oven to 325 degrees Fahrenheit. Line two baking sheets with parchment paper.
In a large bowl, cream the softened butter and powdered sugar together until light and fluffy.
Beat in the salt, lemon zest, lemon juice, and crushed dried thyme until just combined.
Gradually add the gluten-free flour blend and almond flour to the butter mixture. Mix on low speed until a soft dough forms. Do not overmix.
Shape the dough into a log about 1.5 inches in diameter, wrap it in plastic wrap, and chill for 30 minutes.
Remove the dough from the refrigerator. Slice the log into 1/4-inch thick rounds. Place the rounds onto the prepared baking sheets, spacing them about 1 inch apart.
Prick the top of each cookie twice with a fork.
Bake for 15 to 18 minutes, or until the edges are lightly golden brown. The centers should still look pale.
Let the cookies cool on the baking sheet for 5 minutes before transferring them to a wire rack to cool completely.
Notes
For a stronger thyme flavor, use 1/2 teaspoon of fresh thyme leaves instead of dried.
If your gluten-free flour blend does not contain xanthan gum, add 1/2 teaspoon to the dry ingredients.
Store cooled cookies in an airtight container at room temperature for up to one week.