In a bain marie over low heat cook egg yolks and sugar whisking until they get pale and thick. It must reach 140°F/60°C. Remove from heat.
Melt butter.
In a separate bowl, whisk nut butter into warm melted butter.
Little by little mix the nut butter mixture to the egg mixture until combined.
Let the mixture cool until it reaches 113°F/45°C.
Whip 5 egg whites to soft peaks. (Hint: egg whites must be at room temperature)
Fold the whipped egg whites into the batter.
Line a baking sheet with parchment. Butter 8 ring molds and the parchment.
Add 120 g of batter to each mold and refrigerate for at least 1½ hours.
Bake at 350°F/190°C in a preheated oven for 7 minutes or until the edges are cooked and golden.