Preheat oven to 375 degrees.
In a large mixing bowl, cream butter and 1/2 cup of the maple syrup. Whisk in the eggs, then the peanut butter and vanilla, whisking well after each.
Sprinkle oats evenly across surface of wet ingredients, then do the same with the salt, baking powder, chia seeds, and peanuts.
Gently fold all together until well incorporated.
Use a mini ice cream scoop to transfer rounded scoopfuls of dough onto two cookie sheets.
Bake for 15 minutes or until surface is somewhat firm (won't be very brown).
Remove from oven and turn broiler on.
While broiler is heating, use a pastry brush to gently brush the remaining 3 Tbsp maple syrup across the surface of each cookie.
Return each pan to the broiler, one at a time, and broil for about a minute, or until surface is slightly golden.