• In a small bowl, dissolve yeast into warm water. Stir gently and then let rest for about 5 minutes, until mixture gets frothy.
• In the bowl of your mixer (or in a large bowl with a hand mixer), whisk together flour, pumpkin pie spice, and salt. Stir in sugar. Add milk, butter, egg yolks, and yeast mixture and blend together using the mixer’s dough hook (if you don’t have a mixer with dough hook, a hand mixer is fine). Once dough forms, increase speed to medium-high and beat for about 3 minutes.
• Sprinkle dough with flour, cover with a kitchen towel, and put in a warm spot to rise. Let dough rise for about 2 hours.
• Lightly flour a surface and place dough on it. Roll dough out into a square, about ½-inch thick.
• Using a biscuit cutter or the top of a drinking glass, cut out as many rounds as possible (with a 3-inch biscuit cutter, you should get about 14 doughnuts). Place rounds on a lightly floured baking sheet and cover with a kitchen towel, put in a warm spot, and let rise for about 30 minutes.
• In a large stockpot, heat about 2.5 inches of canola oil to 350 degrees. Put doughnuts in hot oil, 2-3 at a time. Let fry for about a minute and then flip over to fry on the other side for another minute, until golden on both sides. 
• Remove doughnuts to paper towel covered plate. Repeat until all doughnuts are fried. Let doughnuts cool slightly.
• When doughnuts have cooled a bit, spoon pumpkin custard in a pastry bag fitted with a wide tip. Insert tip into doughnut and squeeze custard into doughnuts. 
• Drizzle maple frosting over doughnuts and sprinkle crumbled bacon over the tops.

Pumpkin Custard

• In a heat-proof large bowl, whisk together egg yolks and sugar.
• In a separate medium bowl, whisk together flour, cornstarch, and pumpkin pie spice, and whisk the dry ingredients into the sugar/egg mixture. Whisk until smooth. Mix in the pumpkin puree, too.
• In a large saucepan, bring the milk and vanilla to almost a boil. Remove from heat and slowly pour it into the egg mixture, whisking all the time to prevent curdling.
• Pour it all back into the saucepan and continuously whisk over medium heat until it thickens, about 5 minutes.
• Remove saucepan from heat and put custard into a separate bowl. Cover with plastic wrap so plastic is touching the top of the custard. Pop in the fridge to chill.

Maple Frosting

• In a medium bowl, whisk together milk and confectioners' sugar. Add in maple extract and whisk to combine. It should be a good consistency for drizzling.
• If frosting is too thick, add in more milk ½ tsp at a time. If it's too thin, add in more confectioners' sugar, 1 Tbsp at a time.