Preheat the oven to 360ºF / 180°C.
To a large mixing bowl, add the flour, baking soda, salt, whisk together and set aside.
On a bowl of a stand mixer or another large bowl, beat the butter and peanut butter until smooth on a stand or hand mixer. Add white and brown sugars and beat on medium speed until the mixture looks pale and fluffy for 3 minutes.
Reduce speed to low, add the eggs and vanilla essence. Beat until combined for 1 minute.
Add the flour mixture in parts and beat on low to combine.
Using a cookie scoop or ice cream scoop, place the dough into muffin tins, press down with your fingers to flatten slightly on the corners and bottom of the cups.
Bake for around 12 minutes or until lightly browned and mostly set.
Remove from the oven and immediately use a small cup or container to press firmly down in the center to create a well in the cookie dough to form a cup.
Set aside to cool down for 10 minutes. Remove cookie cups from the moulds and place on a wire wrack or a cloth to cool completely.
While the cookie cups are cooling, beat the butter with a mixer until creamy at low speed.
Add the peanut butter and beat well for 3 minutes.
Add the sifted powdered sugar in 1/2 cups at a time and beat until combined. Add the vanilla essence.
Add cream one tablespoon at a time until reach the desired consistency.
Beat on high for 3 minutes until fluffy.
Pipe the peanut butter filling into each cup.
Place one marshmallow twist on top of each and roast with a blowtorch.
Sprinkle chopped roasted peanuts (optional).