O.K., here's my sister Kitty's Peanut Butter Fudge. It never fails for me, but I do use a candy thermometer.
2 cups sugar
2 TBSP butter
3/4 cup milk
3/4 cup peanut butter
1 tsp vanilla
Combine sugar, butter and milk. Bring to a boil and stir until sugar dissolves. Cook to soft ball (236F) stage. Remove from heat and add peanut butter and vanilla (I also add a big spoonful of marshmallow creme). Beat till mixture begins to thicken (only takes a few minutes). Pour into buttered pan.
I'd love to see your recipe joan.