Gluten-Free Flour: Make sure to use a good-quality gluten-free measure-for-measure flour (a 1:1 gluten-free substitute for regular all-purpose flour) that is made up of lighter flours/starches (such as rice flour, tapioca starch, corn starch or potato starch). I do NOT recommend using a gluten-free flour blend that is made up of heavier flours (such as garbanzo bean flour).

Xanthan Gum: Xanthan gum is the replacement for gluten in gluten-free flours, and helps the ingredients better bind together. If your gluten-free flour blend does not already include xanthan gum, make sure to add it in.

Cornstarch: If you are allergic to cornstarch, you may also use tapioca starch or arrowroot starch instead.

Leavening Agents: I used both baking soda and baking powder as leavening agents. If you are Celiac or gluten-intolerant, make sure to use gluten-free baking soda and gluten-free baking powder.

Butter: Make sure to use unsalted butter since we are already adding salt. Brown the butter in a skillet over medium high heat, melting it and then cooking it until caramelized and brown. If you are lactose-intolerant, feel free to use unsalted dairy-free butter instead.

Brown Sugar: I used dark brown sugar, but light brown sugar or coconut sugar will work just as well. If you are diabetic or insulin-resistant, I highly recommend using brown granulated monkfruit sweetener (a 1:1 brown sugar substitute that is zero glycemic index and will not raise your blood sugar).

Sugar: I used white sugar, but cane sugar will work just as well. If you are diabetic or insulin-resistant, I highly recommend using granulated monkfruit sweetener (a 1:1 sugar substitute that is zero glycemic index and will not raise your blood sugar).

Eggs: Eggs help to bind the ingredients together as well as give these gluten-free monster cookie bars a chewy texture, so make sure to add them in.

Vanilla Extract: I like adding vanilla extract for extra flavor, but you if you don’t like vanilla, feel free to leave it out.

Mini M&M’s: Colorful M&M’s are a key ingredient in monster cookies, so make to add them in. We’re using mini M&M’s here, but you can also use regular-sized M&Ms if you prefer. (Most M&M’s made in the US are gluten-free except for the flavors such as pretzel and crispy M&M’s). If you are lactose-intolerant, here’s a dairy-free version you can use.

Semisweet Chocolate Chips: I like adding semisweet chocolate chips for an extra chocolate-y flavor. If you are lactose-intolerant, you can use these dairy-free chocolate chips too. However, feel free to leave them out if you prefer.

Storing: To store, place the gluten-free M&M cookie bars in an airtight container and store at room temperature for up to 3 days.