In a large mixing bowl, combine the oats, vanilla protein powder, cinnamon, chia seeds, and salt. Stir together thoroughly until evenly distributed. This ensures the protein powder and spices are uniformly incorporated throughout the mixture, which is essential for consistent flavor and texture in each ball.

Add the peanut butter, honey, and vanilla to the dry mixture from Step 1 and stir well until combined. The peanut butter acts as a binder, so work it in thoroughly—it should coat all the dry ingredients evenly. Fold in the raisins last, distributing them evenly throughout the mixture. I like to use creamy peanut butter here because it creates a smoother, more cohesive dough than chunky varieties.

If the mixture feels too dry and won't hold together, add the milk 1 tablespoon at a time, stirring between additions until the mixture reaches a sticky, dough-like consistency that holds its shape when squeezed. Once the texture is right, scoop portions using a small cookie scoop or tablespoon and roll between your palms into tight, compact balls—this creates a dense, chewy texture. I find that working quickly and not overhandling the dough prevents the balls from becoming too oily.

Place the rolled balls on a parchment-lined plate or container and refrigerate for at least 30 minutes. This sets the structure and makes them firmer and easier to handle or store. Once chilled, transfer to an airtight container and keep refrigerated for up to one week, or freeze for longer storage.