Preheat oven to 375F degrees. Spray baking sheets with nonstick cooking spray or cover with parchment paper.
In a bowl, combine 1 3/4 cup all-purpose flour with 3/4 teaspoon baking soda and 3/4 teaspoon salt. Using a fork, stir well. Set aside.
In the bowl of a stand mixer or a large mixing bowl with an electric hand mixer, combine 1/2 cup shortening (Crisco), 1 1/4 cups light brown sugar, packed, 3/4 cup creamy peanut butter, 3 Tablespoons milk and 1 Tablespoon vanilla extract. Beat at medium speed until smooth and well-blended.
Add in 1 large egg and mix well.
Slowly begin adding the flour mixture to the peanut butter mixture. Only add a little at a time as you mix it to make sure flour doesn't fly everywhere. Don't overmix, just stir until combined (or you'll get tough cookies.)
Form dough into 1-inch balls and place on cookie sheet about 2 inches apart. I find this easiest with a spring loaded cookie scoop. NOTE: Don't bake too many at a time so you can easily add the antlers, etc without them cooling too quickly.
Then, to make the reindeer face, pinch the bottom half of the cookie with your fingers.
Then smush each one down gently with your hand.
Bake cookies (one sheet at a time) on the middle rack for about 8 minutes.
While the cookies are baking, start getting all your embellishments organized. As soon as the cookies come out, you are going to be working kinda fast.
Once cookies are finished, while still warm, start adding the noses (using the red M&M's). Then add the chocolate chip eyes fairly close to the nose. Just make sure you put them in pointy side up.
Now add the antlers using the chocolate covered pretzel twists. This part can be a bit tricky because those antlers are heavy. So it's important that you don't put them too far to the edge of the cookie. They need to be solidly on the cookie, near the eyes, and gently apply a bit of pressure for a few seconds to make sure they stay in place.
Allow cookies to finish cooling. Finish with the remaining cookies.
Video
Notes
If you are using a stand mixer, you always have to remember to scrape down the sides of your bowl to make sure everything gets incorporated.
The cookies need time to cool completely before you move them. The chocolate will set up and then stick to the cookie. Then you'll be able to move them and store them at that point.
You can use plain mini pretzel twists but you'll need to melt a little chocolate to use to adhere them better to the cookie.