In a small saucepan, combine the milk, water, butter, honey, and salt over medium to medium high heat. Cook until the butter and honey melt, making sure you do not bring the mixture to a boil, which is unnecessary for melting the ingredients. Remove the pan from the heat, and let stand for about 10 minutes, until it’s 110F. Ideally use a thermometer to check, but if you don't have one, you want to wait until the liquid feels lukewarm.
In the bowl of a stand mixer, whisk the flours and yeast together to combine. Pour the lukewarm wet ingredients into the flour, and stir roughly with a spatula until the dough starts to come together.
Fit the bowl onto the stand mixer with the dough hook, and knead on low speed for 10 minutes, until relatively smooth. If you don't have a stand mixer, you may knead by hand, but know that it will be sticky. Do not add more flour, as this will make the buns dense.
Grease a large bowl with the olive oil using your fingers, then shape the dough into a ball and place it inside. Toss the dough to coat in the oil. Cover with plastic wrap and let stand until it doubles in size, about 1 hour.
Divide the dough into 12 portions. Shape each one into a ball by pulling the dough underneath itself and gathering on the bottom (see blog post for photo). Split the balls between two half sheet pans lined with parchment paper (6 on each), and flatten each ball with the palm of your hand until it’s about 3 or 4 inches wide and one inch tall. Cover the trays, then let the dough rise until doubled in size, around 30 to 45 minutes.
Preheat the oven to 400F.
Beat the egg in a small bowl, then brush the tops of the buns with the egg wash. Sprinkle the tops with everything bagel seasoning, sesame seeds, or poppy seeds. Or, you may leave them plain.
Bake for 15 minutes until they are golden brown in color and read 200F with an instant read thermometer. Let cool completely before slicing and serving. Enjoy!
Storage: Because there are no preservatives here, you should only keep these for 2 days at most at room temperature. If you want to store longer, I recommend freezing.Freezing: These will keep in an airtight container in the freezer for up to 2 months. I recommend slicing before freezing, so you can simply reheat them in the toaster straight from the freezer.A note on baking: As with most baking recipes, you want to bake these on the center rack of the oven. I find it better to bake each tray one at a time, so it's truly in the center. If I try to get both racks in at the same time, my oven will brown the top tray more. You can also switch them halfway through.