I love the title screen where you see the cute slimey aliens, they're really the stars of this game! The art of the icea cream truck and the cone mountains in the background are really cool.
I also liked how they slowly melt while waiting for their ice cream, and how the freeze theme was tied into the narrative. Apart from customers slowly melting, the gameplay doesn't really involve the freeze theme though in my opinion. The idea of the main game is also essentially a single-player version of Overcooked, which is fun, but also not necessarily a fresh idea.
For the controls I first tried clicking the ingredients and stuff, maybe you could think about this input method in the future. I think it might be more intuitive. Since you need the key controls from the start, you might also consider just always displaying them, I found myself constantly having to press space anyways.
And finally, for the art I would suggest going for either pixel art or non-pixel art, to my taste it looks better than if you mix the two. You could also look into "mixels", which is when you mix resolutions between or within sprites of pixel art. It happens a lot on this game, and in pixel art it usually avoided because it looks less like a unified visual style!
I have given a lot of criticism, but this game deserves a lot of praise as well. There are two main parts, cute art that is quite unified in terms of colors, nice music and sound effects, and for a game made in 9 days it's quite good! Especially with what seems to be the largest team of the whole game jam. Nice job coordinating everything and producing a whole game together!!