To make the dough, add the instant yeast and sugar to the bowl of a stand mixer equipped with a dough hook or paddle. If using a regular large mixing bowl, that's fine too. Warm the milk to about 110°F (43°C) on the stove or in the microwave. Pour the warm milk over the yeast mixture. Stir gently, cover loosely with a clean towel, and let sit until the mixture becomes frothy, about 5–10 minutes.

Add the softened butter, egg, flour, and salt to the yeast mixture. Mix on low speed for 3 minutes, until a soft dough forms.

With the dough still in the mixer, knead for 5 minutes on low, or knead on a lightly floured work surface by hand for 5 minutes. If the dough feels sticky while kneading, add extra flour 1 teaspoon at a time as needed, just until the dough is soft and only slightly tacky. Avoid adding too much. When the dough bounces back slowly when poked, it’s ready for rising.

Place the dough in a greased bowl and cover with plastic wrap or foil. Let it rise in a warm spot until doubled in size, about 60–90 minutes.

Meanwhile, grease a 9×5-inch loaf pan. Prepare the filling and topping during this time.

To make the cream cheese filling, beat together the cream cheese, butter, Italian seasoning, garlic powder, mozzarella cheese, and salt in a large bowl using a stand mixer with paddle attachment or a hand mixer, until smooth and combined. Cover and set aside.

For the topping, mix together the poppy seeds, sesame seeds, dried minced onion, dried garlic flakes, and coarse salt in a small bowl. Set aside.

Once the dough has risen, punch it down to deflate. Turn it out on a lightly floured surface and roll into a rectangle about 1/4-inch thick. Spread the cream cheese filling evenly over the rolled-out dough.