For the caramelized onions:

These take quite a while to make (30-60 minutes on average) so I've kept them optional for the recipe. I highly suggest making them while your pizza dough is rising or you can make them in advance and double or triple the recipe to use throughout the week.

1. Trim the ends from the onion and remove the dry outer layers of skin. Slice the onion in half, end to end, then thinly slice into half-moons.
2. In a large skillet over medium heat and add the oil and butter. Once the oil is shimmering and the butter is melted, add the sliced onion to the pan.
3. Saute for 8-10 minutes, stirring often, until the onions have started to become translucent and are browning slightly. Season with salt.
4. Reduce heat to medium-low and continue to cook, stirring every 5-10 minutes. If at any point you find that your onions are browning around the edges too much or starting to stick to the pan you can lower the heat and add a small splash of water or broth to the pan. The onions should be lightly caramelized around the 20-30-minute mark and deeply golden between 40 and 60 minutes. You'll want to watch the pan more closely in the final stages of cooking to ensure that the onions don't burn.

For the bratwurst:

1. In a skillet over medium-high heat, add the butter. Once the pan is hot and the butter is fully melted add the bratwurst.
2. Sear for 3-4 minutes on both sides until golden brown.
3. Carefully (slowly) pour in water or beer and cover with a lid. Allow the liquid to come to a boil then reduce heat to maintain a simmer for 3-5 minutes. Remove the brats from heat once they reach about 160 degrees -- they will continue cooking in the oven.
4. Slice the bratwurst into discs at an angle and reserve to the side.

For the mustard cream sauce:

1. In a small saucepan over medium-low heat melt the garlic-infused olive oil (or olive oil + minced garlic) with the butter. When the butter has fully melted, add the flour and whisk to combine fully.
2. Once the mixture has started to simmer and become frothy, add the milk slowly, whisking to combine. The mixture will look chunky at first but will smooth as you whisk.
3. Once the milk is combined, add the stone ground mustard and continue to whisk until combined fully.
4. Season with a pinch of nutmeg. The sauce should have thickened considerably at this point and be fairly smooth. If your sauce is too thick, add additional milk 1 tablespoon at a time, whisking to combine. Remove from heat and reserve to the side until ready to assemble the pizza.

For the rest of the pizza:

1. Preheat your oven to 500 degrees F / 260 degrees C and set a baker’s half sheet to the side.
2. Roll or hand-stretch your pizza dough: If you prefer a classic pie shape with a thicker crust compared to the center of your dough, I suggest hand-stretching your dough. If you prefer your pizza to be an even thickness, I suggest rolling your dough out with a rolling pin. 
   • If you are hand-stretching your dough:
     1. I like to rub a small amount of olive oil into my hands first; this allows me to shape the dough easier without it ripping accidentally from friction.
     2. Press the dough down with the palm of your hand into a disk shape, then use your fingertips to gently press down on the dough disk, further flattening it.
     3. To further extend the dough, I prefer to press one palm on top of one side of the dough and with the other hand lift the alternative side of the dough and gently work the dough outward, pulling very gently with the tips of my oiled fingers (like a very discrete “come hither” motion) to slowly stretch the dough out. Rotate slightly and repeat until the dough is shaped and stretched to your liking. If you find that the dough starts to snap back or is beginning to tear, allow the dough to relax for a minute or two before proceeding again. Transfer your stretched dough to a sheet of parchment paper.
   • If you are using a rolling pin:
     1. I prefer to place my dough between two sheets of parchment paper to avoid the dough sticking to my rolling pin, but if you prefer you can also sprinkle a bit of flour over the dough ball as well as well as wiping some over your rolling pin by hand to prevent sticking instead. Once the dough has been rolled to your preferred size and shape, peel the top layer of parchment paper off (if using). The bottom layer that the dough is resting on can be utilized for your baking sheet. If you find that the dough starts to snap back or is beginning to tear, allow the dough to relax for a minute or two before proceeding again.
     2. Transfer your shaped dough (and bottom sheet of parchment paper) to the reserved baking sheet.
3. Spread the reserved mustard cream sauce over the top of the pizza dough with a spoon.
4. Top the pizza with the shredded Gouda cheese, sprinkling it evenly across the top. Then top with the apple slices, reserved par-cooked and sliced bratwurst, and sauerkraut. I prefer to allow people to add the caramelized onions to the top as desired once the pizza has been baked, but you are welcome to add them to the pizza now before baking if desired.
5. Bake for 14-18 minutes or until the crust has reached your preferred level of crispness and the apples are beginning to brown. I find that pizzas that have a thinner topping layer take less time to bake and heavier-topped pizzas generally take a bit longer to bake so watch your pizza closely after the 14-minute mark and adjust as desired.
6. Top the finished pizza with the reserved caramelized onions if you haven't already added them. Slice and serve warm.