Combine wheat and millet flour with a pinch of salt, make a well in the center and add 1 tablespoon of honey and 150 grams (approximately 5 ounces) of sour cream to the well. Cut butter into small pieces and arrange around the well. Knead all ingredients quickly into smooth pastry. Wrap into foil and refrigerate for about 1 hour. Butter tart pan and sprinkle with 1 tablespoon of breadcrumbs.
Chop 2 tablespoons of pecans and mix with remaining breadcrumbs. Roll out pastry and line pan with it, bake in preheated oven at 200°C (approximately 400°F) for about 15 minutes. Coarsely chop remaining nuts. Rinse and dry plums, pit.
Whisk yogurt with remaining sour cream, remaining honey, eggs, egg yolks, vanilla and brandy. Spread nut and breadcrumb mixture on pastry and top with creamy mixture. Arrange plums on top and sprinkle with remaining nuts. Bake for another 30 minutes. Remove from the oven and cool. Serve.