Preheat oven to 350F/175C/Gas 5, and line cookie sheets with parchment paper.

Using a stand mixer with a whisk attachment (or a hand mixer), beat butter and sugar on medium speed for about 2 minutes.

Add egg, almond, and vanilla extracts, flour, baking powder and salt.

Mix for about 30 seconds, or until combined.

Divide mixture evenly between two bowls.

Add blue food coloring gel to one of the bowls and mix to evenly distribute the coloring. Add a small amount first as you can always add more gel, but can't take it away!

Place both bowls of dough into refrigerator for 5 minutes.

Drain cherries well and dry on a paper towel, patting the top to dry as much as possible.

Take dough out of refrigerator, a dust work surface and hands with flour.

Take about 1 tsp of each color, press together, and gently roll into a ball, taking care not to mix the colors too much.

Place dough ball on cookie sheet and gently press the center with your thumb.

Add a cherry to each thumbprint.

Bake for 9-12 minutes, until lightly golden.

Remove from oven and cool on cookie sheet for 5 minutes, before transferring to wire cooling rack to cool completely.