Line a 9x9 baking dish with parchment paper or butter it lightly.
Melt the salted butter over medium heat in a large saucepan, stirring occasionally.
Add the jumbo vegan marshmallows to the melted butter and stir until smooth.
Remove from heat, stir in vanilla extract, then add Rice Krispies, Golden Grahams, and 1 1/2 cups mini marshmallows. Mix until coated.
Transfer half of the mixture into the baking dish, press down gently, and sprinkle with half of the Hershey's bars and mini marshmallows.
Spread the remaining mixture on top, press down gently, and top with remaining Hershey's bars and mini marshmallows.
Let cool for about 30 minutes before slicing into squares.