In a stand mixer bowl, combine the warm milk, sugar, and yeast. Leave for 5 minutes to activate and bubble up. Add the raisins to a bowl of water to rehydrate slightly.
Add in the salt, eggs, vanilla, lemon zest, and melted butter to the mixer, and whisk to combine. Add in the flour and turn on the mixer and knead it for 6 minutes on low. Then drain the raisins thoroughly and add them to the dough. Knead for an additional 2 minutes.
Lightly oil a large bowl. Transfer the dough to the bowl, cover with plastic wrap, and allow it to rise for about 1 ½ hour in a warm location.
Form the remaining dough into a ball and place into a greased, round baking dish, about 9 inches wide and 4 inches deep.
Allow the dough to rise for about another 1 ½ hours.
Meanwhile, preheat the oven to 350 degrees F.
Bake for 40-45 minutes. Cover the top with foil at 20 minutes in baking to keep it from getting too brown.
Let cool in the pan. Once it's cool enough to handle, remove it from the pan.
Mix the powdered sugar, vanilla, and milk to form a glaze, then pour it onto the cooled paska. Optionally sprinkle with Easter-colored sprinkles.