In a large, wide pot, heat some olive oil and saute the onions and garlic. Drain the liquid out of the can of tomatoes into a large bowl. Add the tomatoes to the onions and garlic and saute, breaking the tomatoes up into small bits with your spoon or spatula, until the onions and garlic are soft and translucent.
Add the tomato paste and stock to the bowl with the tomato juice and whisk until the tomato paste has dissolved. Pour into the pot and bring to a boil. Reduce heat and simmer about 20 minutes or until the mixture has reduced and thickened a bit.
Meanwhile, in a medium bowl, stir together with the flour, baking powder. In another bowl or measuring cup, beat the egg into the buttermilk. Pour it over the flour mixture, stir in seasoning and cheese and stir until a thick dough forms.
Scoop the dumpling dough into the simmering soup in heaping tablespoons (I used a cookie scoop, the dough will be a bit sticky) in a single layer and cover. Continue to simmer about 12-15 minutes or until big, fluffy dumplings form. Serve immediately.