Preheat oven to 350F/ 180C. Mix butter, sugar, and orange zest in medium bowl until creamy. Add in egg whites and mix to combine. Separately, mix milk and 1 tbsp. orange juice and set aside to curdle. Add flour and milk mixture to the butter mix, in 3 increments. Starting with the flour and ending with the flour. Fold in poppy seeds.
Pour batter in Ultra Pro 2-Qt./2 L Casserole Pan. Bake for 25 minutes or until toothpick inserted in center comes out clean.
Make the glaze
While quick bread is baking, mix together powdered sugar and orange juice to create a glaze.
Let bread cool slightly, top with glaze and serve.