In a small saucepan over low heat, heat the milk and 1 tablespoon of the sugar until very warm (120 to 130 F). Pour into a large mixing bowl, and sprinkle over the yeast. Allow to stand until foamy, about 15 minutes.
Sift 1 cup of the flour over the yeast mixture and with a wooden spoon, stir until a batter forms. Cover the bowl with a clean dish towel and leave in a warm place (80 F to 85 F) until mixture looks puffy and spongy, about 1/2 hour.
In another bowl or a 4 cup measure whisk the eggs and egg yolks together with the vanilla extract, grated lemon zest, and salt.
Sift another 2 cups of flour over the risen yeast flour mixture, and make a well in the center. Pour in the egg mixture, and stir with a wooden spoon until the mixture becomes a soft, sticky dough; the dough should be as soft as possible, so do not add more flour unless it is very wet.
Using your hand, spread the butter over the dough and work into the dough, folding it over itself and kneading into the dough until the butter is completely incorporated. Cover with the dish towel and leave to rise again in a warm place until doubled in volume, about 3 hours.
Butter a 2 pound coffee can. Line the bottom with nonstick baking parchment, and butter again.
Punch down the dough and turn onto a lightly floured surface. Sprinkle the raisins, golden raisins over the dough, and knead until evenly distributed throughout the dough.
Form the dough into a ball shape, and ease into the coffee can. Cover and leave to rise again until the dough reaches the top of the can, about 1 1/2 hours.
Preheat the oven to 400°F Brush the top of the dough with a little milk and if you like sprinkle with about a tablespoon of sugar. Bake for 15 minutes, then reduce the oven temperature to 350°F and bake about 1/2 hour longer; if the paska browns too quickly, cover with foil. Remove to a wire rack to cool in the can for about 5 minutes, then carefully unmold, top side up, to cool completely. Makes 1 loaf.