Line an 8-inch square pan with parchment paper, leaving overhang for easy lifting.
If using rolled oats and you want a smoother base, blend them into oat flour.
In a bowl, mix peanut butter, rolled oats or oat flour, ground almonds, maple syrup, and a pinch of salt until fully combined.
Press the mixture firmly into the prepared pan in an even layer.
Melt the dark chocolate with the coconut oil until smooth, then stir well.
Pour the melted chocolate over the base and spread evenly. Chill until set, then lift out and slice into bars.