1cupdark chocolate chips or chopped bittersweet chocolate, (5 oz.)
1/2cuppecans, toasted and coarsely chopped, for the topping
1/4vanilla bean, split and scraped
1cuppowdered sugar, sifted
1-3teaspoonswater or milk
Position a rack in the center of the oven and preheat it to 350º. Lightly grease a 9" cake pan and line it with a round of parchment paper (or use an unlined springform pan).Combine the butter and sugar in a stand mixer fitted with the paddle attachment, and beat on medium speed until fluffy and light, a few minutes. Add the eggs one at a time, beating to combine after each and scraping down the sides of the bowl as needed.
Meanwhile, stir together the yogurt and squash in a measuring cup and sift the dries into a medium bowl. Alternate adding the dries and yogurt mixture to the butter mixture, beginning and ending with the dries, in 3 additions. Mix on low until just combined after each addition, then mix in the chocolate pieces.Spread into the pan and bake until a tester inserted comes out mostly clean (a few crumbs are ok), 45 minutes or so. Let cool. Invert onto a plate, remove the parchment, then flip onto another plate so it's right side up. Spread with the glaze and sprinkle with pecans.
Combine the butter and vanilla pod and scrapings in a small saucepan. Cook over medium heat, swirling occasionally, until it turns golden and smells nutty. Combine with the powdered sugar in a bowl, and whisk in enough water to make a pourable glaze (if the mixture 'breaks', don't despair - keep whisking in small amounts of water or milk until it comes back together.)
Nutritional values are based on one of eight servings.