Preheat your oven to 200°C/400°F (fan-forced) and line a baking tray with baking paper.
In a food processor grate your garlic, onion, apple, carrot and baby spinach. Alternatively, grate / finely chop by hand.
Mix together with the thyme, mustard, salt, pepper and pork mince until well combined.
Halve the sheet of puff pastry and divide the mince mixture evenly along the centre and length of both halves of the pastry.
Roll and pinch together the seam, placing it face down on the baking tray.
Brush with the milk, sprinkle with the chia seeds and cut into approx. 8 pieces (per log).
Bake for 30 minutes or until the pastry is puffed and golden brown.