Preheat a fan-forced oven to 200°C or a conventional oven to 220°C.
Place two Ironclad Junior pans in the oven for 5 minutes to preheat.
Melt the chopped chocolate and vegan butter in a heatproof bowl over a double boiler, or in short bursts in the microwave, stirring until smooth.
In a separate bowl, whisk together the sugar, oat milk and vanilla.
Pour in the melted chocolate mixture and whisk until combined.
Sift in the flour, cocoa powder, baking powder and salt. Fold gently until just combined.
Carefully remove the Junior pans from the oven and lightly grease them with coconut oil or vegan butter.
Divide half the batter between the two pans.
Place one square of chocolate in the centre of each, then cover with the remaining batter.
Bake for 9–11 minutes, until the edges are set and the centres remain soft. Bake for 9 minutes for a looser molten centre.
Rest for 1–2 minutes before serving.
Serve straight from the pans or run a knife around the edges and carefully invert onto plates.
Finish with chocolate shavings, fresh berries and vegan ice cream.