STEP 1: MAKE THE MULLED WINE JAM (START FIRST — NEEDS TO COOL)
Combine the red wine, orange juice, orange zest, cinnamon stick, star anise, cloves, and ginger in a saucepan. Bring to a gentle simmer and cook for 10–15 minutes until the wine has reduced by about one third and the spices have infused deeply. Strain out all the whole spices and discard. Return the spiced wine to the pan and add the sugar and lemon juice. Stir to dissolve. If using jam sugar (which contains pectin), bring to a rolling boil and cook for 4–5 minutes, testing for set on a cold plate — a dollop should wrinkle when pushed. If using regular sugar, add 2–3 tablespoons of liquid pectin at this stage. The jam should be thick and spreadable, firm enough to stay in the biscuit window without running but soft enough to remain jammy. Pour into a clean jar and cool completely before using as a filling.

STEP 2: MAKE THE VANILLA SHORTBREAD DOUGH
In a large bowl or food processor, combine the flour, cornflour, caster sugar, and salt. Add the cold cubed butter and rub in with your fingertips (or pulse) until the mixture resembles fine breadcrumbs. Add the vanilla extract and bring together into a smooth dough — it will seem dry at first but will come together with gentle pressing. Do not overwork: shortbread's signature crumble comes from minimal gluten development. Wrap in cling film, press flat, and refrigerate for at least 1 hour until firm.

STEP 3: ROLL AND CUT THE HEARTS
On a lightly floured surface, roll the chilled dough to approximately 4mm thick — even thickness is essential for uniform baking. Using a heart-shaped cutter (approximately 3 inches / 7cm), cut 24 hearts. From 12 of these hearts (the tops), use a smaller heart cutter to create a window in the centre. Place all hearts on lined baking trays and chill for a further 15 minutes to prevent spreading in the oven.

STEP 4: BAKE THE SHORTBREAD
Preheat oven to 325°F (160°C). Bake for 12–15 minutes until pale golden at the edges but still relatively light on top. Shortbread should not be deeply browned — it continues to firm as it cools. The base hearts can bake 1–2 minutes longer. Cool on the trays for 5 minutes, then transfer carefully to a wire rack.

STEP 5: PREPARE THE MARZIPAN LAYER
Roll the marzipan very thin (about 2mm) between two sheets of cling film. Using the same large heart cutter, cut 12 marzipan hearts. Place one on each base biscuit. The marzipan acts as a moisture barrier between the jam and the shortbread, preventing sogginess, while adding a subtle almond undertone without dominating.

STEP 6: ASSEMBLE THE HEARTS
Spoon or pipe approximately 1 teaspoon of the cooled mulled wine jam onto each marzipan-topped base. Spread gently to within 3mm of the edges. Dust the window-cut top hearts generously with icing sugar. Place a dusted top heart on each jam-covered base, pressing very gently to adhere. The ruby jam should be visible through the heart window against the white sugar and golden shortbread.