Step 1

Grease a 9x13" baking dish, set aside.

Step 2

Melt butter in a large bowl on high heat in the microwave. Melt in 30 second increments, checking the butter and swirling the bowl after each 30 seconds. Depending on the starting temperature of your butter, it may only take 30 seconds.

Step 3

Stir the marshmallows into the melted butter to coat. Return the bowl to the microwave to melt the marshmallows, again in 30 second increments at high heat. Stir after each 30 seconds. When marshmallows are melted, stir well until butter is completely incorporated into the marshmallow (Note: At first it will look like there is too much butter, and it will appear separated from the marshmallow. Keep stirring vigorously and it will incorporate after30-60 seconds). Stir in vanilla.

Step 4

Fold cornflakes and almonds into the marshmallow mixture. Stir well until uniform. Transfer the mixture to the prepared baking dish. Press firmly into the dish, but not so firmly as to crush the cornflakes (this will be very sticky! Use the back of a large, oiled spoon or oil the palms of your hands). Let set at room temperature, about 2 hours. Once the mixture has set, cut into squares. Store in an airtight container or bag at room temperature or in the freezer.