In a bowl of a stand mixer ( or a large mixing bowl) whisk together the flour and salt. In a measuring cup measure out the warm water then stir in the yeast and sugar. Let sit for 5 minutes until yeast starts to bubble. 

With the mixer on low, add the oil slowly to the flour then add in the yeast mixture. Keep on low until the dough forms a shaggy ball. Raise speed to medium low ( around a 4 on the settings) and knead for five minutes. 

Transfer the dough ball to a lightly oiled bowl (or you can remove the dough from the mixer bowl, oil in then add the dough ball back in) and cover with plastic wrap and a towel. Place in a warm, draft free area for one hour. 

At this time pre-heat your oven to 500 Deg F with a pizza stone, pizza steel or baking sheet that can withstand high temps placed on the highest rack about 6-8 inches below the broiler elements. This is important since half the cooking is done with the broiler. Heat for an hour before baking (same amount of time the dough needs to rise).

Mix together the crème fraîche with the salt, pepper and nutmeg. Keep chilled until ready to use. 

Slice the bacon into lardons ( thin, widthwise strips) and cook in a skillet ( cast iron preferably) until about ⅔ of the way cooked. Transfer to a paper towel lined plate. 

Remove the core from the apples using an apple corer or cutting into quarters and cutting out then thinly slice. Almost paper thin slices. 

Onion - remove peel, cut in half and slice super thin. 

Once the dough is ready - remove and cut into 4 even pieces. About 215 grams each. Working with one piece of dough at a time. Roll out to a thin rectangle about 10 by 15 inches then place on a piece of parchment paper. 

Spread one-fourth of the seasoned crème fraîche on top then add a fourth of each the bacon, onions then apples and sprinkle with a teaspoon or so of fresh thyme. Repeat with remaining dough to prepare all the flatbreads at once ( if you have the counter space).

If your baking stone/steel or baking sheet is large enough you can bake two at a time, if not bake one at a time. 

Slide onto your heated stone/steel/baking sheet on the parchment ( using a pizza peel if you have one) and bake for 2 minutes. After 2 minutes, remove the parchment and switch your oven to broil and broil for 2 more minutes, turning the flatbreads after a minute. If you want an even darker more charred crust, cook for another minute. Transfer the flatbread to a cutting board and repeat with remaining ingredients to make four flatbreads. If baking more than one at a time the same steps work for both and time to cook. 

Cut into wedges and serve. These go great with a nice German Weissbier.