PREPARE THE COOKIE DOUGH

1. In a small mixing bowl, whisk together the gluten free 1:1 flour, baking soda, salt, cinnamon, cardamom, and ginger. Set aside.
2. In a large mixing bowl with an electric hand mixer (or the bowl of a stand mixer fitted with the paddle attachment), mix together the butter, light brown sugar, and granulated sugar for ~1-2 minutes until creamy and smooth.
3. Add the vanilla extract and egg and mix until well incorporated, scraping down the sides and bottom of the bowl as needed.
4. Add the dry ingredients and mix on low until no flour streaks remain.
5. Using a rubber spatula or wooden spoon, stir/fold in the oats until they are evenly distributed throughout the batter.
6. Chill in the refrigerator for 30 minutes (just to hydrate the flour; it will remain fairly soft) NOTE: I would not recommend chilling the dough for much longer than 30 minutes as it can dry out too much!

BAKE THE COOKIES

1. Preheat the oven to 350F and line two large baking sheets with parchment paper.
2. Use a 1 tbsp cookie scoop to scoop the dough into balls (20g each). Place the cookies on the baking sheet, 2 inches apart (12 per cookie sheet). NOTE: You can also scoop the dough with a 1 tbsp measuring spoon and roll them between your palms to create a round shape.
3. Bake one sheet at a time on the middle rack of the oven for 7-9 minutes. The edges should be lightly golden and the tops will be puffed up and pale (it’s best to remove them when they seem a little underbaked!)
4. Immediately after removing from the oven, use a round cookie cutter or the rim of a small bowl to gently swirl the cookies to create an even round shape.
5. Allow the cookies to cool on the pan for 10 minutes before removing them and placing on a wire cooling rack.

PREPARE THE STRAWBERRY RHUBARB CREAM

1. Add the diced strawberries, diced rhubarb, sugar, and lemon juice to a small saucepan and stir together.
2.  Place the pan on the stove over medium (or low-medium) heat and stir frequently until the fruit begins to release their juices and comes to a boil.
3.  Reduce the heat slightly and simmer, stirring occasionally, until the fruit breaks down/softens and the liquid has thickened slightly and reduced (roughly 15 minutes).
4. Remove the pan from the heat and pour the reduction through a fine mesh sieve into a bowl to separate out the liquid (the liquid will be used in the filling). Allow the liquid to fully cool before proceeding.
5. In a large mixing bowl or the bowl of a stand mixer with a paddle attachment, beat together the butter, cream cheese, vanilla extract, and salt until smooth and creamy.
6. Add half of the powdered sugar and mix until combined and smooth.
7. Add 1 tbsp of the strawberry rhubarb reduction and mix until fully combined.
8. Add the remaining powdered sugar and mix to combine. Then continue to mix until light and fluffy. NOTE: Add more powdered sugar if the mixture needs to be thickened.
9. Place the cream filling in a piping bag with a large round tip. NOTE: You can place the filled piping bag in the refrigerator for a few minutes to help it firm up a little before assembling the cookie sandwiches if needed.

ASSEMBLE THE COOKIES

1. Pipe the filling in the center of the flat side of half of the cookies (almost to the edge of the cookie, with about 1/8 inch of space ).
2. Top with the remaining cookies and press down slightly so the filling comes to the edge of the cookie (but without coming out the sides!)