Add butter, sugar, milk, and cocoa powder to a medium saucepan. Bring to a boil over medium-high heat, whisking often. Reduce heat to low, and simmer for 3 minutes.
Remove from heat and stir in salt, vanilla extract, and peanut butter until completely incorporated. Stir in oats and flax meal.
Refrigerate mixture for 30 minutes to an hour; then shape into tablespoon sized balls. Roll in powdered sugar if desired.
Notes
*Any milk will work: whole milk, 2% dairy, unsweetened almond milk, coconut milk.*Use coconut oil and non-dairy milk for dairy-free.*Use sunflower seed butter for nut-free