Preheat oven to 180ºC. Grease a 12-hole doughnut baking tin.
In a bowl, combine flour, baking powder and salt. Stir to combine.
In a separate bowl, add peanut butter, butter and Natvia. Using a stand mixer, beat for a few minutes until combined. Scrape down the sides of the bowl throughout if necessary.
Add eggs one at a time, mixing in between.
In a small jug, add vanilla to the milk. Alternate between adding the dry ingredients and the vanilla milk to the wet ingredients, mixing in between each addition. Begin and end with the flour mixture.
Divide batter among doughnut moulds. Place into the oven and bake for 15 minutes, or until an inserted skewer comes out clean. Allow to cool for 10 minutes before removing from pan. Allow to cool completely before glazing.
To make the glaze: add Natvia and cornflour into a high-powered blender. Blend for 10 seconds until a very fine powder. Pour into a bowl.
Add in water and vanilla and whisk until silky. Add the salt and stir.
Place doughnuts on a cooling rack over a tray. Pour over glaze and quickly sprinkle with chopped roasted peanuts.