Melt the butter, marshmallows, and ube spread together - In a large saucepan, melt the butter over low heat until fully melted. Add the marshmallows and continue stirring until melted and smooth. Add the ube spread and stir until evenly combined. Take the saucepan off the heat. - Make sure to keep an eye on the marshmallows while melting them. If they are overheated, they can become tough and chewy instead of soft and fluffy.

Add the Rice Krispies cereal - Add the Rice Krispies cereal to the saucepan and mix gently until all the cereal is coated evenly with the marshmallow-ube mixture. - It's important to mix gently instead of vigorously to avoid crushing the cereal and losing its texture.

Press the mixture into a baking pan - Line a 9x13 inch baking pan with parchment paper or grease it with butter. Transfer the cereal mixture to the pan and press it down firmly and evenly using a spatula or the back of a spoon. - To make the job easier, use a piece of parchment paper or plastic wrap to press down on the mixture without getting your hands sticky.

Let the treats cool and set - Let the treats cool for at least 30 minutes at room temperature, or until they have set and are firm to the touch. Cut into squares using a sharp knife and serve. - If you prefer crispy and crunchy treats, you can place them in the refrigerator for a short time before cutting them. Be sure to remove them from the refrigerator and let them come to room temperature before serving to avoid them becoming too hard.