Preheat the oven to 350°F (175°C). Arrange the oven racks in the upper and lower thirds of the oven. Line two large baking sheets with parchment paper.

Add the brown sugar, cashew butter, and softened butter to a large mixing bowl. Using an electric mixer, beat on medium speed for about 1 minute, or until the mixture looks creamy and fluffy. Scrape down the bowl when necessary.

Add the egg, lemon zest, lemon juice, and vanilla extract. Beat for about 30 seconds, just until everything is evenly incorporated.

In a separate bowl, whisk together the rolled oats, all-purpose flour, whole-wheat flour, baking soda, baking powder, cinnamon, and salt.

Turn the mixer to low and gradually add the dry ingredients to the wet mixture. Mix only until a thick, evenly combined cookie dough forms.

Fold the dried blueberries and chopped pecans into the dough with a spatula until evenly distributed.

Divide the dough into 16 portions, using approximately 2 1/2 tablespoons for each cookie. Arrange them about 2 inches apart on the prepared baking sheets.

Gently press each portion down with your fingers or the back of a spoon. These Lemon Blueberry Breakfast Cookies should be slightly flattened before baking.

Bake for approximately 12–15 minutes. Halfway through baking, switch the positions of the baking sheets so the cookies bake more evenly.

Remove the cookies when the edges are lightly golden while the centers remain soft. Cool on the baking sheets for 5 minutes before transferring them to a wire rack.