- STEP 1
Beat the butter and sugar together until pale and fluffy. Beat in the vanilla for a few secs, then use a wooden spoon to stir in the flour with ¼ tsp salt. Roll the dough into 36 small balls (the easiest way to get this right is to divide the dough into quarters – each quarter then makes 9 balls).
- STEP 2
Heat oven to 180C/160C fan/gas 4. Line two baking sheets with baking parchment. Squish 2 balls of dough together on the paper, keeping the ‘round’ edges of the balls at the top, but pinching together at the base where they meet, so they make a rough heart shape. Flatten with the palm of your hand to a biscuit, then press in heart-shaped ‘dent’ for the jam – thumbs and fingers are perfect for this. Repeat with remaining dough balls leaving a little space between each finished heart shape for spreading.
- STEP 3
Spoon the jam into a food bag (or disposable piping bag), snip off the end and pipe roughly 2-3 tsp jam into the thumb-heart dips you have made in each biscuit. Bake for 8-12 mins until pale golden and crisp. Cool on the trays.
- STEP 4
Mix the custard powder and icing sugar, then dribble in enough water to make a runny icing. Drizzle all over the cooled biscuits, allow to set for at least 10 mins, then serve or store in a biscuit tin.