Preheat the oven to 180°C and lightly spray a doughnut pan with cooking oil.
In a medium size bowl add flour, baking powder and salt and mix gently with a whisk to combine.
In a large bowl, using an electric mixer, beat together the egg, sugar and vanilla. Add in the cookie butter and continue to beat until combined. Add in dry ingredients and mix through, slowly adding in the dairy-free milk until the batter is smooth.
Pour batter into a large piping bag or ziplock bag and cut off the tip. Pipe the batter into the doughnut pan ensuring each hole is only half full.
Place in the oven and bake for 8 minutes or until the tops spring back when lightly touched. Let cool in the pan for 2 minutes and turn out onto a wire rack to cool completely.
To make the glaze, add the glaze ingredients to a large bowl and using an electric mixer, beat until smooth and creamy. You want the glaze to be thick but still runny enough to coat the doughnuts so add a little more milk if needed to thin it out.
Dunk the top of each doughnut into the glaze and then place on a wire rack with a piece of baking paper under it to collect any excess glaze that drips off. Decorate each doughnut with crushed biscoff cookies and set aside until the glaze has set. Store the doughnuts in an airtight container at room temperature for 1-2 days or in the fridge for 3-4 days.