In a medium saucepan, add the peanut butter, unsalted butter, brown sugar, and salt. Place over medium heat and cook, stirring constantly, until the butter is melted and beginning to bubble.
Remove from heat and whisk in the vanilla extract.
Use a wooden spoon or rubber spatula to mix in the powdered sugar, 1/4 cup at a time, until fully incorporated and the mixture is pulling away from the sides of the pan. Allow to cool to room temperature.
Line a large baking sheet with parchment.
Roll a heaping tablespoon of the cooled peanut butter into a ball, then gently form into an oval. Place on prepared baking sheet and lightly press to flatten slightly and form into the shape of a peanut butter egg.
Repeat with remainder of the peanut butter filling. Refrigerate until chilled, about 30 minutes.
Place the chocolate chips into a bowl. Microwave in 20 second increments, stirring in between, until melted and smooth.
Dip a peanut butter egg into the chocolate and use a fork to flip until fully coated. Pick up with the fork and gently shake to remove excess chocolate.
Place back on baking sheet and repeat with remaining eggs. If using, top with sprinkles. Refrigerate until chocolate is hardened, about 30 minutes.
If using white chocolate or dark chocolate to drizzle/decorate, place in a small bowl and microwave in 20 second increments, stirring in between, until melted and smooth.
Drizzle over eggs or place in piping bag fitted with a small tip to decorate. Refrigerate until set. Place in an airtight container and refrigerate until ready to serve.