Preheat the oven to 350 degrees F. Spray a 13 by 9-inch baking pan with cooking spray. Put a medium glass bowl over a pot of simmering water. Add the chocolate chips and 1 tablespoon canola oil. Stir frequently until the chocolate melts, then remove from the heat and let cool a bit.
In a large bowl add the sugar, eggs, and vanilla. Mix until well combined and the sugar has dissolved, about 2 minutes. Sift together the flour, cocoa powder, pumpkin pie spice and chili powder. Add to the egg mixture and stir well until everything is combined. Add the remaining oil and mix with an electric hand mixer until smooth. Stir in the melted chocolate and mix well. Pour into the prepared pan and bake until a toothpick comes out clean when inserted into the brownie, about 30 to 35 minutes. Cool and dust with powdered sugar before serving.