Monster Cookies

Step 1: Heat the oven to 180°C / 350°F (160°C fan-forced). Line three trays with baking paper.

Step 2: Put the flour, oats, baking soda and salt in a medium bowl. Mix with a wooden spoon just until combined.

Step 3: Put the butter in a microwave-safe bowl. Microwave on high in 20-second increments until almost melted, then stir with a wooden spoon to finish melting it with the residual heat.

Tip: Keep the butter barely melted rather than hot and fully liquid.

Step 4: Add the remaining wet ingredients to the butter. Mix vigorously with a wooden spoon until smooth.

Step 5: Add the dry ingredients to the wet ingredients and mix until most of the flour is incorporated. Add the chocolate chips and M&Ms, then mix until evenly dispersed and no flour is visible.

Step 6: Roll the dough into 18 balls, 3 tablespoons each (about 4.5 cm / 1.8 inches in diameter). Portion the dough with a size 20 cookie scoop if you have one, then roll each portion. Place the balls on the lined trays at least 7.5 cm / 3 inches apart.

Tip: If the dough is too sticky to roll, refrigerate it for 5 minutes to firm up.

Step 7: Bake two trays for 15 minutes, switching their oven shelf positions at the 8-minute mark.

Step 8: If using the optional toppings, press chocolate chips onto the cookies while they are hot. Lightly press the M&Ms halfway into the surface; they will set in place as the cookies cool.

Step 9: Cool the cookies on the tray for 10 minutes so they finish cooking and set, then transfer them to a rack and cool for another 10 minutes. Bake the third tray in the meantime. The cookies are fragile while hot. Once fully cool, store in an airtight container in a cool pantry for up to 5 days.