Preheat your oven to 350°F and line a baking sheet with parchment paper. While the oven heats, measure out all your dry ingredients—flour, brewer's yeast, cinnamon, salt, oats, milled flaxseed, and whole flaxseed—into separate small bowls. This advance prep ensures you won't scramble mid-mixing and helps you catch any ingredient mistakes early. Make sure your egg is at room temperature, as it will incorporate more smoothly into the wet ingredients.

In a large mixing bowl, combine the melted and cooled coconut oil with the packed brown sugar. Stir vigorously for about 30 seconds until well combined—the mixture should look slightly grainy. Add the room temperature egg and vanilla extract, then beat with a fork or whisk for about 1 minute until the mixture becomes pale and slightly fluffy. This aerating step helps develop a better texture in the finished cookies. I like to beat this mixture longer than it seems necessary because it creates a lighter, more tender cookie.

In a small bowl, whisk together the milled flaxseed and water to create a gel-like binder. Let it sit for 30 seconds so the flaxseed fully absorbs the water and becomes creamy—this is what gives these cookies their structure and helps with the lactation-boosting properties. Pour this flaxseed mixture into the wet ingredient base from Step 2 and stir until fully incorporated, scraping down the sides of the bowl to ensure nothing gets missed.

Add the flour, brewer's yeast, cinnamon, and salt to the wet ingredient mixture from Step 3. Stir gently with a wooden spoon or spatula until just combined—you're not making a smooth batter here, just bringing everything together. Stop stirring once you don't see any obvious streaks of flour, as overmixing can develop the gluten in the flour and make the cookies tough. I find that using a spatula and folding motions rather than aggressive stirring keeps these cookies tender.

Add the oats, raisins, and whole flaxseed to the dough from Step 4 and fold gently until everything is evenly distributed. The dough should come together nicely and look studded with oats and raisins. Be careful not to overmix at this stage—you want to maintain the dough's structure and create cookies with a pleasant texture from the mixed ingredients.

Using a cookie scoop or spoon, portion the dough onto your prepared parchment-lined baking sheet, spacing the cookies about 2 inches apart. Gently press each cookie flat with the bottom of a glass or the back of a spoon—these cookies won't spread much, so flattening them now ensures even baking and a consistent texture throughout.

Bake in your preheated 350°F oven for 12 minutes, or until the edges are lightly golden and the centers feel set when gently pressed. The cookies will continue to firm up as they cool, so don't overbake or they'll become dry. Remove from the oven and let them rest on the baking sheet for 5 minutes before transferring to a cooling rack, which helps them hold together better.