1. Preheat oven to 425 degrees. Melt 1 tablespoon butter in a saute pan over medium heat. Stir in shallots and rosemary; cook until shallots are soft, about 2 minutes. Set aside.

2. In a large bowl, whisk the flour, baking powder, 4 tablespoons mustard powder, and salt. Using two knives or a pastry cutter, cut in the remaining 1/2 cup butter with dry ingredients until the mixture is coarse and crumbly. Cut in the shortening.

3. Combine milk, grainy mustard, and shallot-and-rosemary mixture. Make a well in the center of dry ingredients, and pour in milk mixture. Slowly mix in flour mixture until all of it is incorporated. Make sure the dough is mixed well but not overworked. Turn dough out onto lightly floured work surface. Pat into a rectangular shape about 1 inch thick. Using a 2-inch biscuit cutter, cut out biscuits, and transfer to a parchment-lined baking sheet.

4. Transfer to oven to bake. Combine remaining tablespoon mustard powder with honey, stirring until smooth. When biscuits are puffed up and golden brown, about 25 minutes, remove from oven, and brush with mustard glaze. Return to oven, and bake 5 minutes more. Serve hot.