Preheat the oven to 350°F. Line a 8x8" pan with parchment paper and lightly spray with non-stick spray. I like to leave enough parchment paper to easily lift them out.
In a large bowl, whisk the butter, vegetable oil, sugar and brown sugar. Add the eggs and vanilla and whisk about a minute.
Next add the flour, cocoa powder and salt. Stir just until barely combined. Add chocolate chips and 1/2 cup M&M's and stir until smooth. Be careful to not over mix. Pour batter into pan, then top with remaining 1/4 cup M&M's.
Bake for 20-25 minutes, or until a toothpick comes clean. Be careful not to over bake.
Allow to cool slightly in pan and then you can remove the brownies with the parchment paper to finish cooling. Once cooled, cut into 16 squares with a plastic knife.
This recipe easily doubles. Cook the doubled recipe in a 9x13" pan. You may need to cook a few minutes longer. Freezer instructions:Allow to cool completely and then wrap individual brownies in plastic wrap. Store in a freezer container or zip top bag for up to 3 months.