Isn't it bad to leave partially mixed ingredients sitting out?

[She'll go along with it anyway, snagging a basket to start putting ingredients in. Eggs obviously, and sugar... she already has Lon-Lon milk in her sylladex, this no-name variety clearly isn't up to par. Vanilla... maybe powdered sugar for frosting?]

My friend prefers sweets that are not too terribly artificial. What sort do you think might be good?