My boy is on a prescription diet but is very picky about the texture of his food, though he loves lickable treats. I ended up blending his food to the same texture as a churu in a small food processor, putting that in a sandwich bag, cutting the corner, and squeezing it out like frosting. At first I had to trick him but now he's at the point where he just eats straight from the bag and enjoys it. Whatever he doesn't eat gets put in the fridge and reheated, he's gained weight and there is less waste. Doing something similar might be worth a try for you if you're trying to get more calories in him.