Bring the mixture to boil, cover and let simmer for about 10 min. Then uncover and continue to cook for another 7 to 10 min. until thickened and the rhubarb is soft. Let cool and set aside. If this doesn't boil long enough it will make your muffins fall (it may have happened to min).
COFFEE CAKE BATTER
Preheat the oven to 325F. Line 2 muffins tins with paper liners.
In a large bowl of a mixer cream the room temperature butter and sugar together until light and fluffy. Add eggs one at a time and then add in the vanilla, yogurt, and milk. Set aside.
In a medium bowl whisk together flour, baking powder, baking soda, and salt.
Add the dry ingredients slowly to the wet ingredients with the mixer on low. Mix until just together. Set aside.
STREUSEL TOPPING
For the streusel topping, combine flour, brown sugar, and salt. Add the cold butter and mix to a crumble mixture in a small bowl using a pastry cutter, fork, or your fingers and set aside.
FILLING MUFFIN TINS
For the muffins, add in enough batter to fill about 1/3 of the muffin cups, then add in a large tablespoon of rhubarb compote and swirl slightly using a chopstick, skewer, or knife. Finish with more batter to fill about 3/4 full and top with a generous amount of streusel topping.
Bake for 25 to 30 minutes or until the muffins are lightly browned on top and a tester in the center comes out clean.
Cool for 5 minutes in the pans and then remove and cool completely on cooling racks.