In the work bowl of a food processor, pulse oats until almost ground and uniform in size but not too powdery. Add raisins, and pulse until finely chopped. Add flour, cocoa, salt, cinnamon, baking soda, and baking powder; pulse just until combined.
In the bowl of a stand mixer fitted with the paddle attachment, beat butter and brown sugar at medium speed until fluffy, 2 to 3 minutes, stopping to scrape sides of bowl. Add eggs, one at a time, beating well after each addition. Beat in molasses and vanilla until combined. With mixer on low speed, add oats mixture in two additions, beating until combined after each addition. Cover and refrigerate for 30 minutes.
Preheat oven to 350°F (180°C). Line several baking sheets with parchment paper.
Using a 1½-tablespoon spring-loaded scoop, scoop dough (about 30 grams each), and roll into smooth balls. Place 2 inches apart on prepared pans.
Bake until bottom edges are golden but centers look a little wet, 8 to 12 minutes. (Do not overbake.) Let cool on pans for 5 minutes. Remove from pans, and let cool completely on wire racks.