In a large bowl, combine flour, baking powder, baking soda and salt and stir to combine. Set aside.
In a separate large bowl use a hand or stand mixer to cream together the softened butter, sugar, eggs, buttermilk and almond extract on low speed for 20-40 seconds. Once combined stir in flour mixture, sliced almonds and poppy seeds until just combined.
Spray a large muffin tin with cooking spray (or use paper muffin liners) and divide the batter equally among 12 cups. The cups should be filled to the top. If desired sprinkle additional sliced almonds over top before baking.
Once all the batter is used place the muffins in the oven on the center rack at 425 degrees for 5 minutes. After 5 minutes reduce heat to 375 degrees and bake 10-15 more minutes. The tops should just start to get some color and a toothpick should come out clean when they are finished. Enjoy warm plain or with butter!
Leftover Storage: Store leftover muffins in an airtight container at room temperature for up to 4 days. Enjoy cold or heat in the microwave for 10 seconds to enjoy warm.
Freezer Option: To freeze let the muffins cool completely and wrap in foil then place them into a freezer bag for up to 2 months. When ready to eat you can de-thaw in the refrigerator over night or warm in microwave 30 seconds.
Recipe Alterations: You can swap the buttermilk out for cow's milk or a milk alternative like almond milk if you wish.
Additional Almonds: I like to top unbaked muffins with almonds before baking. This step is optional and you do not have to add them.
Mini Muffin Option: Prepare the batter per the recipe instructions, but bake for only 7-10 minutes at 375 degrees.