Use leftover Halloween candy to make this delicious skillet cookie.
Preheat oven to 350°F.
In a large bowl, whisk together the flour, baking powder and salt.
In a second large bowl, add the butter and sugar. Using a stand mixer with a paddle attachment, beat until fluffy, about 3 minutes. Beat in the eggs and vanilla. Pour in the dry ingredients and beat until just combined. Fold in 1/2 cup M&M's.
Coat a 10-inch cast-iron skillet with nonstick cooking spray. Using an offset spatula, spread batter into skillet. Scatter remaining 1/4 cup M&M's on top and sprinkle with turbinado sugar. Bake 25 minutes.
Cover with foil, then bake 5 to 10 minutes, until the cookie begins to pull away from edges of the pan but is still soft. Cool 30 minutes before slicing into wedges.