4th of July Monster Cookie Bars

In a large bowl, use an electric mixer to cream ¾ cup unsalted butter (not margarine) (i.e. 1 ½ sticks), ¾ cup granulated sugar, and ½ cup light brown sugar for 2 minutes until light in color.

Add in 2 eggs, 3 tablespoons light corn syrup, and 2 teaspoons vanilla extract. Mix until combined.

Add ¾ cup creamy peanut butter and mix until combined. Stir in 1 teaspoon baking soda and ½ teaspoon salt. 

Add 1 ¾ cups all-purpose flour and 1 ¾ cups quick oats and mix until just combined.

Mix in chocolate chips [adjustable](¾ cups) and m&m's (¾ cups)[/adjustable]. 
Note: For this step, note that we're only using [adjustable]¾ [/adjustable] of chocolate chips & [adjustable]¾ [/adjustable]cups m&m's inside the dough so that we can reserve the other [adjustable]¼ [/adjustable]to sprinkle on top.

Drop dough into a greased or parchment-lined metal 9x13" pan and spread until smooth. The dough will be a little sticky, so it's easiest to drop the dough into small pieces instead of adding it in one big blob. 
Sprinkle the remaining [adjustable]¼ cup chocolate chips, ¼ cup of m&m's, and ¼ cup sprinkles[/adjustable] on top and gently press into the dough.

Bake at 350°F for 28-32 minutes until edges and top are lightly golden brown and the center no longer looks wet. Do not overbake or your bars can get dry and will not be as soft and chewy. You want the cookie bars to be lightly brown on the edges and top. Remove from oven and place entire pan on a cooling rack. 

Allow the cookie bars to cool completely before removing from pan. If you cut the bars when they're still warm, they will be crumbly and fall apart. For the cleanest cuts, they need to be fully cooled and/or slightly chilled before cutting.

Slice into 12-24 squares, then enjoy! To keep fresh, cover pan with plastic wrap or place bars in airtight container for up to 3 days (after that they start to dry out). See notes below for freezing tips.