Preheat oven to 350℉ and line a baking sheet with parchment paper.
In a medium saucepan, melt butter at medium heat.
Add milk powder and oatmeal. Mix constantly, and continue cooking until the butter browns. The mixture will look foamy (no longer bubbly), and there will be small golden brown flecks of milk solids.
Transfer the butter mixture to a large heatproof bowl.
Add sugar and mix until combined.
Add egg, vanilla, cinnamon, nutmeg, espresso and salt. Mix until combined.
Add flour, baking powder, chocolate and raisins. Mix until just combined. There will be no more visible flour streaks.
Scoop cookies with a 1.5 tbsp scoop onto the prepared baking sheet, leaving 2 inches (5 cm) around each cookie. Flatten until around 1/2 inch (1 cm) thick.
Bake for 10-12 minutes, or until the cookie goes from looking glossy and wet to dry and matte in the center.