Italian Plum Bread

Mmmmm...having to stop myself from going into the kitchen to eat more of this. My neighbors have an Italian Prune Plum tree...three years ago it put out massive amounts of fruit and I made jam and conserve with it. Every year I wait for these delicious plums. But since then...there haven't been many plums. Luckily this year we got a bunch in our Tonnemaker Farm CSA box. I looove having this fruit box. The plums weren't very good fresh...they were a little too mealy and the flavor wasn't as tart as I like. So I decided to cook them and found this recipe on food.com. My slight adaptation below:

1 cup butter, at room temperature
2 cups granulated sugar
4 eggs
1 teaspoon vanilla extract
3 cups all-purpose flour
1 teaspoon salt
1 teaspoon cinnamon
1 teaspoon cream of tartar
1/2 teaspoon baking soda
3/4 cup plain yogurt
1 cup walnuts
3 cups diced blue Italian plums

Preheat the oven to 350°F. Lightly grease two 9 x 5 inch loaf pans.
In a large bowl, cream together the butter and sugar until light and fluffy. Add the eggs and beat well. Add vanilla.
In a separate bowl, combine the flour, salt, cinnamon, cream of tartar and baking soda. Add the dry ingredients and yogurt alternately to the creamed mixture, beginning and ending with the dry ingredients.
Stir in the nuts and plums. Divide the batter between the two loaf pans.
Bake for 60 minutes, or until a toothpick inserted in the center comes out clean.
Let the pans cool on a rack for 10 minutes, then turn the loaves out of the pans and cool completely on the rack. Makes 2 loaves.