Preheat oven to 350 degrees F.
Melt the peanut butter with 3 tablespoon of butter. Set aside 1 tablespoon of butter.
Stir in the remaining ingredients up to the eggs. Wait to add eggs until you taste batter.
Taste batter for sweetness, adjust if needed, then stir in eggs until combined.
Pour batter into a parchment lined loaf pan.
With the remaining tablespoon of butter, melt that together with the chocolate. Add chocolate stevia then taste and adjust. Stir until smooth.
Drizzle the melted chocolate into the loaf. Stir around with a butter knife.
Bake for 45 minutes.
Allow to cool 15 minutes before removing and slicing.
Enjoy or toast!