Sift the flour into a bowl with the thickeners, spices and salt. In a separate bowl, combine the sugar and oil and beat it with a mixer until you get a fluffy cream.
Add the eggs one at a time and mix well with a mixer. Also add the milk while stirring. Combine the wet and dry mixtures and add the flour in parts, until fully absorbed. Mix well to obtain a homogeneous mixture.
Then, add the pumpkin and walnuts, and stir it well. Put the mixture into a buttered and floured cake mold, leaving about a cup of it in the mixing container. To this small amount of the blend, add 1 teaspoon of cocoa, mix and pour it over the rest of the cake.
Bake at 356°F (180 °C) for about 1 hour. Remove, allow it to stay 15 minutes in the mold, then place into a tray.