Line the crockpot with parchment paper or foil.

Arrange the saltine crackers in a single layer at the bottom of the crockpot.

In a saucepan, melt the butter and brown sugar over medium heat, stirring constantly until the mixture is bubbly and smooth.

Pour the butter-sugar mixture over the arranged saltine crackers, making sure to cover them evenly.

Cook on low for 2 hours, stirring gently every 30 minutes to ensure an even coating.

After 2 hours, turn off the crockpot and sprinkle the semisweet chocolate chips over the top.

Drizzle the peanut butter over the melted chocolate and mix gently to combine.

Spread the chocolate-peanut butter mixture evenly over the crackers.

Top with optional milk chocolate chips and sprinkles, if desired.

Let it cool completely before lifting it out of the crockpot and breaking it into pieces.