Preheat the oven to 350F.
In a medium bowl, beat or stir together the butter, peanut butter and sugars until creamy and smooth; beat in the egg, vanilla and salt.
Stir in the oats and baking soda, then the chocolate chunks. Drop by the spoonful onto a parchment-lined baking sheet, spacing them well apart (they spread out pretty thin), and bake for 15 minutes, or until spread out and golden. Let them cool for a bit on the baking sheet, then remove them with a thin spatula. Eat them warm.