Chowder, "Shnitzel Quits": Mung is trying to convince Shnitzel to return to his catering business, promising him things like more days off and big raises, when Chowder offers him a mold-filled cup. This is actually a pudding cup — the very first thing the group cooked together. Shnitzel happily swallows it, signaling his return. (He then bloats up and becomes violently ill afterward, but it's the thought that counts, right?)
The ending of "Hey, Hey, it's Knishmas" is definitely enough to bring a tear to someone's eye. Particularly the part where Gorgonzola cries because of how nice Chowder is and the part where Chowder actually kisses Panini!
The end of "Mung On The Rocks" is the most romantic thing ever, showcasing that, despite their fights, Mung and Truffles definitely love each other.
"Chowder Grows Up." The finale explains everyone's happy endings. Mung and Truffles get to retire on the beach, Shnitzel and Endive end up together, Gazpacho lives his dream of being a comedian/fruit vendor, Gorgonzola happily rivals Chowder, and Chowder grows up to be a mentor to young Scraps and marries Panini, having 50 kids. It's a sweet ending about growing up to help others.