Preheat oven to 350F. Grease a 9x5 loaf pan with 1 Tbs. of butter. Be sure to get the edges so that the cake doesn't stick to the pan! Flour lightly, tap out excess flour, and set aside.
In a small bowl, toss cranberries in 1 Tbs. flour. (Don't skip this step! This will prevent cranberries from sticking together.) Set aside.
In a stand mixer fitted with the paddle attachment, beat butter and sugar on high speed until light and fluffy, about a minute. Lower speed slight and add eggs, one at a time. Scrape down sides of the bowl with a rubber spatula. With mixer on low speed, add baking powder, salt, and half of remaining flour. Add half of milk, and when incorporated, add the rest of the flour, followed by the remainder of the milk. Scrape down sides of the bowl, mixing again on low speed if needed. Fold in lemon zest and floured cranberries. (It's fine to dump in any extra flour that wasn't stuck to the cranberries.)
Pour mixture into prepared pan and bake until a toothpick inserted into the center comes out clean, 55-65 minutes. Remove from oven and allow to cool for 15 minutes.
Set a cooling rack on top of a piece of parchment or wax paper (to catch any glaze that may drip if you glaze the cake). Remove cake from pan and allow to finish cooling on the wire rack.
In a small saucepan over medium-high heat, cook sugar and lemon juice until sugar has melted, stirring occasionally. Continue to cook until it has come to a boil. Allow to boil for 30 seconds before removing pan from heat. Allow to cool slightly, as glaze will thicken a little as it cools.
Pierce top of cake all over with a toothpick, or better yet, a wooden skewer (which will go deeper than the toothpick). Use a pastry brush to apply warm glaze to cake. (My cake was still warm when I glazed it.)