1. Preheat oven to 325°F. Butter a large (12-cup) Bundt pan. Arrange whole rose geranium leaves in the bottom of prepared pan sticking them on with a dab of soft butter. Dust the pan with flour, shaking out excess.
2. Combine flour, salt, and baking soda and reserve.
3. Cream Plugrá Butter and sugar until light and fluffy.
4. Beat in eggs, one at a time, then add vanilla, the grated zest, and minced rose geranium leaves.
5. Alternating and beginning and ending with the dry ingredients, add the flour mixture and buttermilk to the batter.
6. Carefully pour batter into the pan so as not to disturb the leaves and bake for 1 hour and 10 minutes, or until just set in the middle. Cool before removing from pan and dust with confectioners' sugar.