Open the box and remove the sealed bag of King Arthur GF Bread & Pizza Mix and the small yeast packet; discard the box (do not discard the yeast). Set the mix and yeast packet aside.

Warm 1 cup (240 ml) milk to 110°F. Pour the warm milk into a small bowl or measuring cup, stir in 1 tablespoon (21 g) honey, then add the yeast packet and stir. Let sit 5 minutes to activate the yeast.

Fit a stand mixer with the paddle attachment. Crack 4 large eggs into the mixer bowl and beat on medium-low speed for about 60 seconds.

Add 1/2 cup (100 g) sugar and 2 tablespoons (30 ml) oil to the beaten eggs. Mix on medium-low for 30 seconds to combine.

Pour the entire bag of bread mix into the mixer bowl. Mix on low speed until no dry streaks remain, scraping down the bowl as needed.

With the mixer on low speed, slowly pour the activated yeast-and-milk mixture into the bowl until fully incorporated; the mixture will be a loose batter at this point.

Still on low speed, slowly pour in 3/4 cup (170 g) melted butter. Once the butter is incorporated and the batter looks smooth, increase the mixer to medium speed and beat for 5 minutes. The mixture will be a thick batter (not a traditional wheat bread dough).

Remove the bowl from the mixer, cover tightly with plastic wrap, and refrigerate for 30 minutes.

While the batter chills, prepare a 9×5-inch loaf pan: coat it with butter and line the pan with a strip of parchment paper so the loaf can be lifted out after baking.

Remove the chilled batter from the refrigerator and spread it into the prepared loaf pan. Use a large ice-cream scoop or a spoon to create a textured, domed top typical of brioche.

Place the filled pan in a warm, draft-free spot and let the dough rise for about 1 hour, or until the batter is approximately 1 inch above the top edge of the pan.

Preheat the oven to 350°F while the loaf is finishing its rise.

Bake the risen loaf in the preheated oven for 40–45 minutes, rotating the pan halfway through baking. If the top browns too quickly, loosely tent the loaf with aluminum foil. The loaf is done when the internal temperature reaches 190°F.

Remove the loaf from the oven and let it cool completely in the pan, about 2 hours, before removing from the pan and slicing.