Stir the peanut butter, powdered sugar, and vanilla extract together in a bowl until the mixture forms a smooth, thick dough.
Scoop out teaspoon-sized portions and roll them between your palms into small oval shapes that resemble acorns. Place them on a parchment-lined baking sheet.
Chill the shaped pieces in the refrigerator for 20 minutes so they firm up.
Melt the chocolate chips in the microwave in 20-second bursts, stirring between each until smooth.
Dip each chilled peanut butter piece into the melted chocolate, leaving the top third exposed. Immediately press one pretzel stick into the top of each truffle to act as the stem.
Return the finished truffles to the baking sheet and chill again for 15 minutes until the chocolate sets.