Preheat your oven to 350°F (180°C). Line a square baking pan with parchment paper.
In a medium saucepan, melt the butter over low heat. Once it starts to melt, add the golden syrup. Stir until everything mixes and looks smooth.
Remove the saucepan from the heat. Add the oats and sunflower seeds. Stir well so everything gets coated with the buttery syrup.
Spoon the mixture into the baking pan. Press it down flat using the back of a spoon or your hands. Make sure it’s packed tight and even.
Bake for 20-25 minutes or until the top is golden and smells toasty.
Let it cool in the pan for 10 minutes. Then take it out and slice it into squares while it’s still a little warm. It holds shape better this way.