Sift the flour, salt, baking powder, baking soda, and cumin together in a bowl.
Once sifted, stir in the oregano and basil. Add the cold butter and rub into the flour with your fingertips until the mixture resembles breadcrumbs. Alternatively, you could use a food processor on pulse for this step.
Mix together the pumpkin purée and buttermilk, and using a fork, incorporate it into the flour mix taking care not to overmix.
Once the dough comes together, place it in the refrigerator for about 30 minutes.
Meanwhile, chop the sundried tomatoes into a fine paste. You might need 1-2 teaspoons of olive oil to get a smooth consistency. Set aside.
Remove the dough from the fridge and place it on a lightly floured surface.
Using a rolling pin, roll the dough into a rectangle ½ inch (~1 ½ cm) thick. Spread the sundried tomato paste over the dough and sprinkle with walnuts.
Starting at one end, roll the dough into a log and the cut in 8 equal pieces.
Place the pieces in a deep baking dish lined with parchment paper (an 8- or 9-inch or 20 cm cake tin does the job well), brush the top with heavy cream and bake in a preheated oven at 220° C/430° F for about 18-20 minutes.