1. Preheat oven to 400ºF. Line a baking sheet with parchment.
2. Place 2 cups oats in food processor; process until finely ground. Transfer to large bowl and whisk in flour, baking powder and salt. Toss in raisins. Add honey and milk to bowl with dry ingredients and mix with a rubber spatula until just moistened.
3. Scrape down sides of bowl, shape dough into a ball and transfer to baking sheet. With well-floured hands, pat gently into a 7-inch round and sprinkle evenly with remaining 2 Tbsp. oats. Using a very sharp knife, cut a shallow X in top of loaf.
4. Bake until loaf is well browned and sounds hollow when tapped on underside, 55 to 60 minutes. Transfer loaf to a wire rack and let cool for at least 1 hour before slicing and serving.