Preheat the oven to 180 C / Gas 4. Line a 20 x 30cm baking tin with baking parchment.
Melt the soya margarine and Trex® in a fairly big saucepan on a low heat.
Add the molasses sugar then the black treacle stirring steadily to blend all ingredients. Once everything has blended turn off the heat.
Add 50g of the seeds keeping back 10g to scatter over later. Stir in the oats until you have an even mix and all the oats are covered with the mixture.
Spoon the warm mixture into the tin spreading out flat until you have an even depth. Use a spatula or back of spoon and try to do this before the mixture cools too much. Scatter the remaining seeds onto the surface of the flapjack and smooth over to embed them into the mixture, this ensures the seeds are visible on top.
Place the baking tin into the oven and bake for 15 to 18 minutes until the mixture turns brown, pumpkin seeds will split giving a nice rustic look.
Leave to cool for ten minutes or so before scoring the sections for cutting. Leave to cool for a further 20 minutes before sliding out of the tin and cut the squares.
Once cool, transfer to an airtight container, use greaseproof paper between layers to prevent the squares sticking together.
Cut into 50 squares they make a nice tea time snack about 110 calories of slow burn energy with a little sugar hit.