Prepare the pan:

• Spray a 9×9-inch pan with non-stick spray. Line it with parchment paper and spray again.

Brown the butter:

• In a large pot over medium heat, melt the butter. Continue cooking until it turns golden brown and smells nutty (about 2-3 minutes). Remove from heat immediately.

Melt the marshmallows:

• Add 8 cups of mini marshmallows and sea salt to the browned butter. Stir until smooth. If needed, return to low heat briefly.

• Stir in vanilla extract.

Mix with cereal:

• In a large bowl, pour the melted marshmallow mixture over the Rice Krispies cereal. Stir until well coated.

• Fold in the remaining 2 cups of mini marshmallows while still warm for extra texture.

Layer the treats:

• Press half of the mixture into the prepared pan, spreading evenly.

• Spread dulce de leche over the first layer.

• Top with the remaining Rice Krispies mixture, pressing gently to even out.

Cool and serve:

• Let the treats cool at room temperature until set. Cut into squares and enjoy!