Preheat oven to 350°F. Spray two baking sheets or line them with parchment paper.
Cream butter, granulated sugar and salt until just combined.
Add eggs and vanilla extract and mix to combine.
Sift together flour, xanthan gum, baking powder and spices. Add to butter mixture and mix slightly. Add muesli and continue to mix until thoroughly combined.
Scoop cookies onto prepared baking sheets (about 2 Tbsp per cookie) and bake for 15 - 17 minutes until the edges are slightly brown. Let cool slightly on baking sheets then remove cookies to a wire rack to cool completely.