Preheat the oven to 400 degrees. Spray a baking sheet with cooking spray or line it with parchment paper.

In a large bowl combine the flour, sugar, cinnamon,baking powder, baking soda, and salt.  Mix well.

Cut the butter into small pieces and add the butter to the mixture. Use your fingers and mix the butter into the flour mixture until it resembles wet sand. 

In a small bowl whisk together the yogurt, vanilla extract, and egg. 

Add wet ingredients to dry ingredients and mix until just combined.

Gently fold in the rhubarb.

Turn dough onto floured surface and knead for 30 seconds or until dough comes together.  Shape into an 8 inch circle. 

Cut the circle into 8 pieces and place on the prepared baking sheet.  Sprinkle with coarse sugar.

Bake for 15-18 minutes or until they begin to brown.  Remove from oven and transfer to wire rack. Cool completely.