Coffee Cake (with peaches)

A character in a book I'm reading (Strange Fits of Passion by Anita Shreve) eats coffee cake and I find myself thinking about coffee cake for days afterward. So finally, I decide to make one. I adapted this from the Joy of Cooking and scattered a few pieces of
peach over the top before I put on the streusel. It was exactly what I was hoping for. Lots of decadently sweet streusel topping (you could cut it in half), but the cake itself wasn't too sweet or rich, and the bits of peaches from our tree were like little gems of summer goodness.

Yogurt Coffee Cake (with Peaches)

for the streusel topping:
2/3 c. all-purpose flour
2/3 c. pecans
2/3 c. brown sugar
5 tbs. butter, melted
1 tsp. ground cinnamon
1/4 tsp. salt

Pulse pecans in food processor until chopped, then add remaining ingredients and pulse until the mixture resembles coarse crumbs.

for the cake:
2 cups flour
1 tsp. baking powder
1 tsp. baking soda
1/2 tsp. salt
1 1/4 c. plain nonfat yogurt
1 tsp. vanilla
4 tbs. butter
1 cup sugar
2 large eggs
2 1/2 cups peaches (or other fruit, like apples, cranberries, raspberries, etc.), optional

Preheat the oven to 350. Grease a 9x13 inch pan. Whisk together the flour, baking powder, baking soda, and salt. In another bowl, combine the yogurt and vanilla. In a large bowl, beat butter and sugar on high speed until lightened in color and texture, 3 to 4 minutes. Beat in eggs one at a time. Add the flour mixture in 3 parts, alternating with the sour cream mixture in 2 parts, beating on low speed or stirring until smooth and scraping the sides of the bowl as necessary. Scrape the batter into the pan and spread evenly. Sprinkle the fruit over the batter. Sprinkle the streusel over the fruit. Bake until a toothpick inserted in the center comes out clean, about 25-30 minutes without fruit and about 40-45 minutes with fruit.