Sift confectioners (powdered) sugar.

Grease an 8 x 8 pan, or line with parchment paper.

Melt butter in a medium-size saucepan set to medium heat.

Add brown sugar, salt, and milk to melted butter.

Stir frequently until you start to see bubbles. Then start a 2-minute timer.

Continue to boil and stir for 2 minutes.

Remove from heat immediately. Stir in peanut butter and vanilla extract.

Beat with a hand mixer until smooth.

Slowly add in the powdered sugar and combine thoroughly until blended.

Scraping the sides of the bowl, pour into the prepared pan.

Cover and allow to cool on the counter at room temperature until firm.

Cut into 1-inch squares.