Microwave Cinnamon Minute MugCake

1 T butter  – soften, 10-15 seconds MW
2 T sugar   – stir in
1 egg           – could share one egg >> 2 mugcakes
2 T sour cream  – stir in
1-2 drops  vanilla essence
1/4 c flour  – mix in briefly
1/8 tsp (pinch) baking powder

CRUMB TOPPING (optional, or not)
in separate ramekin or bowl – mix with fingers a few
1 T butter, 2 T flour, 1 T brown sugar,  1 t cinnamon

Add crumb onto top of mug mixture.

Cook  1 min 20 secs. Cool for a bit.
Serve with or without yoghurt or ice cream.