Monster Cookies are a mash-up of choc chip, peanut butter, and oatmeal cookies. They’re crispy on the edges and chewy inside, littered with bright M&Ms and melty chocolate chips, and are as fun to make as they are to eat!
What are Monster Cookies? They’re a mash-up of peanut butter, oatmeal, and choc chip cookies, typically chunky, chewy, and loaded with M&Ms and choc chips. The name may come from the monster mash-up of ingredients, though they’re exactly the sort of cookie a Cookie Monster would go mad over!
Ingredients in Monster Cookies
1. For the Monster Cookie Dough
The cookie dough is based on the Brown Butter Oatmeal Choc Chip Cookie recipe, except the butter isn’t browned here — with so many other flavours going on, including peanut butter and plenty of chocolate, it simply isn’t necessary.
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Peanut butter – Use the commercial spread type such as Bega (Australia), Jif or Skippy (US), or Sun-Pat (UK), which contain sugar, salt, and stabilisers. Do not use natural peanut butter made with 100% peanuts and no added sugar or oil — the dough and cookies will turn out too dry and crumbly.
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Oats – Ordinary rolled oats only. Do not use quick-cooking oats, steel cut oats, or flavoured sweetened porridge sachets. Oats give these cookies great chewiness and lovely texture.
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Flour – Regular plain/all-purpose flour. Self-raising flour won’t work here and will cause the cookies to bake up like rock cakes.
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Baking soda (bicarbonate of soda) – Helps the cookies rise and spread. If you substitute baking powder using the standard 1:3 conversion, the cookies will bake up thicker and puffier with a less chewy interior.
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Brown sugar – Used exclusively (no white sugar) to give the cookies a caramel-like flavour and a rich brown colour.
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Egg – One fridge-cold large egg (approximately 50–55g/2oz in the shell). Using a cold egg helps stiffen the dough so it doesn’t need to be chilled before rolling into balls.
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Unsalted butter, melted – Melted butter means no need to soften it beforehand. Cut it into pieces before melting so it melts evenly.
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Salt – Brings out the flavours in the cookie, and pairs especially well with peanut butter.
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Vanilla extract – Adds a subtle layer of flavour that complements rather than overwhelms the peanut butter.
2. The Add-Ins
M&Ms and chocolate chips are the classic Monster Cookie add-ins, and this recipe uses a generous 1½ cups in total. Feel free to swap in or add whatever you like — nuts, dried fruit, peanut butter chips, or toffee chips all work well.
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M&Ms – Plain M&Ms (no nuts or crispy rice). The recipe uses 1 cup (200g) mixed into the dough, plus about 3 tablespoons (35g) pressed onto the surface straight out of the oven. In Australia, a 180g “snack and share” bag works fine — just top up with extra chocolate chips or other add-ins to make up the difference.
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Chocolate chips – Dark chocolate chips (called semi-sweet in the US) are used here, but any variety works. You can also chop up a block of chocolate instead. The recipe calls for ½ cup, giving you a generous amount of melty chocolate in every bite alongside the M&Ms.
