line a slice tin 26cm x 6cm (10.5in x 6.4in) with baking paper
soften the butter (do not melt) add dextrose and using your mixer or hand held beater cream the butter and sugar until light and fluffy
sift in the flours, and work into the butter and dextrose mixture until a soft dough forms,
roll out to fit your slice pan prick gently all over dough with a fork
bake for about 20 mins and starting to slightly colour
One cooked set aside to cool
Once your base is cooling, start on your marshmallow
Using a whisk or fork, combine gelatine and ⅓ cup of cold water in your mixer bowl and set aside for a 5 - 10 minutes to bloom.
Combine dextrose and ⅓ cup hot water in a saucepan heat, until boiling and then turn the heat down to low and leave for around 10 mins, make sure the dextrose dissolves and the syrup is clear.
Add the hot syrup to the gelatin mixture and beat on low speed until incorporated.
beat sugar and gelatine mixture on high for 10 -15 minutes (depending on your mixer) you will know it's ready as it should be very thick, white and glossy, and hold soft peaks when you lift the mixer out.
Add vanilla and ( food colouring if using) and beat until thoroughly combined .
Spread on top of your cooled shortbread base Smooth top with a damp spatula and sprinkle with coconut threads, chopped nuts or sprinkles
Keep in an airtight container for up to 1 week
Recipe by thatsREALyummy at https://www.thatsrealyummy.com/marshmallow-slice/