Preheat the oven to gas 4, 180°C, fan 160°C and line 2 large baking sheets with nonstick baking paper. Using an electric whisk, mix the peanut butter, dairy-free butter alternative, golden syrup, sugars and vanilla in a bowl until smooth.
Add the four and mix again until combined to a soft dough. Transfer to a floured surface, sprinkle more four on top, then roll out the dough to 1cm thick. Use a 7cm round cookie cutter to cut out 20 cookies, rerolling the dough as needed; transfer to the baking tray.
Spoon a tsp jam into the centre of each cookie, then bake for 10 mins or until golden and just beginning to crisp at the edges. Transfer to a cooling rack to cool completely.
Divide the ice cream between 10 of the cookies and top each with 1 tsp jam. Place the remaining cookies on top, jam side down, and gently push down to sandwich.
