Which TV painter was known for his "happy little trees"?

In 'Sesame Street', which Muppet loves cookies? In 'Sesame Street', what color is Elmo? Who created 'The Muppet Show'? Which children's TV host famously wore cardigan sweaters and sang "Won't You Be My Neighbor?" Which children's series featured host LeVar Burton encouraging kids to read? Which long-running NBC sketch comedy show premiered in 1975? Who created 'Saturday Night Live'? Who hosted 'The Tonight Show' from 1962 to 1992?