Preheat oven to 200°F (95C).

In the bowl of a stand mixer fitted with a paddle attachment, combine 3 cups (375g) flour, sugar, cornstarch, yeast, and salt. Stir until ingredients are well-combined.

In a small saucepan¹ combine milk, water, and 5 ½ Tablespoons butter (reserve remaining 1 ½ Tablespoon for greasing the pan) on the stovetop over low heat. Stir occasionally until butter is melted and mixture reaches 110-115°F / 43-46°C (If the milk mixture becomes too hot, just remove it from the heat and allow it to cool down to the correct temperature range before proceeding)

With your stand mixer on low speed, slowly pour milk mixture into the bowl, stirring until combined.

Add lightly beaten egg and egg yolk and increase speed to medium, stirring until completely combined (be sure to scrape down the sides and bottom of the bowl as needed to ensure all flour is absorbed).

If you have one, switch your paddle attachment out for a dough hook and continue to stir on medium-low speed. Gradually add up to remaining ½ cup (65g) flour + additional as needed. What you are looking for is a dough that clings to itself and pulls away from the sides of the bowl. It should develop a soft, elastic texture and will still be slightly tacky to the touch but shouldn’t be very sticky. You may need less or more flour than the additional ½ cup indicated, go by the texture of your dough rather than measurements.

Transfer your dough to a lightly oiled, heatproof bowl and cover tightly with plastic wrap. Allow to rest in a warm place (I usually place mine on top of my preheating oven) for 10 minutes.

While your dough is resting, prepare a 9x13 glass² baking dish. Use your remaining 1 ½ Tablespoons of butter and melt this in your dish. I like to just set the butter in my baking dish and pop it in the oven for a few minutes (since my oven is already running) until melted.

Once dough has rested, transfer to a clean, lightly floured surface and divide into 15 pieces, shaping each into a smooth, round ball.

Arrange into prepared dish and cover with aluminum foil

Transfer covered dish to 200F oven and turn off your oven. Leave the covered dish in your warm (but now turned-off) oven to rise for 15 minutes.

After 15 minutes, remove dish from oven but leave it covered. The rolls will continue to rise while your oven preheats.

Preheat oven to 350F (175C).

Once oven is preheated, remove foil and lightly brush rolls with additional milk, if desired (helps encourage a browned top).

Transfer to 350F (175C) oven and bake for 18-20 minutes or until rolls are cooked through and beginning to turn a light golden brown on top (do not over-bake rolls or they will be dry).

Serve warm, if desired prepare honey butter glaze by melting together 2 Tablespoons salted butter and 1 Tablespoon honey and brushing over rolls while they are still warm.