Preheat oven to 350º. Prepare a 10 cup bundt pan, by buttering very generously and dusting with flour, knocking out any excess flour.

Measure the topping ingredients into the bowl of the food processor - pulse until the nuts are chopped in medium pieces and the other ingredients well combine. Distribute half of this mixture into the bundt pan, and reserve the remainder in a small bowl.

In the same bowl of the food processor [no need to wash it out], finely grind the clementines.

One at a time, add the sugar, oil, egg, vanilla and buttermilk, pulse after each addition, until completely incorporated.

In a medium bowl, whisk together the flour, salt and baking soda.

Add the dry ingredients to the bowl of the food processor and pulse until incorporated. Don't overmix - this will probably take about about 6 to 8 pulses.

Scrape half of the batter over the topping in the bundt pan.

Distribute the second half of the topping ingredients over the batter.

Finally, scrape in the remainder of the batter, and smooth out evenly.

Bake for about 40 to 45 minutes, until a tester inserted near the center comes out clean.

Cool in the pan for about 5 minutes, and then invert onto a cooling rack. Serve warm or room temperature. You can top with a sprinkling of powdered sugar, or some whipped cream, if you like.