Blend the oats to a fine powder in a food processer.
Melt the maple syrup and coconut oil on a gentle heat in a pan or in the microwave. It will take about 2 mins. Stir in the vanilla extract if using.
Pour the melted coconut oil and syrup over the oat mixture and mix well until you get a moist ‘dough’.
Spoon into a greased/lined baking pan, or as I have done, spoon into moulds.
Chill for 30 mins until it firms up, or, if you are impatient like me, pop in the freezer for 10 - 15 mins.
Melt the marmalade for a minute of so, just so it is easier to work with. You can do this in short bursts in the microwave, or in a pan on a gentle heat. Spread over the oat base or spoon over the top of the individual moulds to make a thin layer and return to chill. Meanwhile, melt the chocolate. You can do this either in the microwave in short bursts, stirring after 1 minute (be careful as you can get hot spots and it can burn easily) or in a bowl resting over a smaller bowl of hot/boiling water (this is called a bain marie). Stir through the peanut butter, then return to your heat source for a further minute.
Pour or spoon over the oat/marmalade base and spread to cover. If using orange zest or nuts, scatter on top of the chocolate before it sets and return to chill.