In a mixing bowl, add the bread flour, oats, baking powder, baking soda, and salt. Mix well.

Melt the butter in a light-colored saucepan over medium-low heat. Stir occasionally until it turns golden brown and smells nutty (5-8 minutes). Pour the browned butter into a bowl and allow it to cool down until just warm.

Add the sugar and whisk well.

Then, add the egg, milk, and vanilla and whisk until well incorporated and emulsified.

Add the dry mixture and using a rubber spatula mix just until no dry ingredients are left.

Fold in the raisins and place the bowl with the cookie dough in the fridge while the oven is preheating.

Preheat the oven to 355F (180C) and line 2 baking sheets with parchment paper.

Scoop 24 cookie dough balls (I used a 2-tablespoon cookie scoop) onto the prepared baking sheets leaving 2" (5 cm) in between. Bake for 12 minutes in batches or until the cookies have spread, puffed up, no longer look wet on top, and turned a golden-brown color around the edges.

Remove from the oven and let them cool down for 5 minutes on the tray. Then, transfer onto a cooling rack to cool down completely. Bake another batch of the cookies.