Preheat your oven to 350°F (175°C). Thoroughly grease a 10-cup bundt pan and dust with flour.
In a medium bowl, whisk together the flour, baking powder, salt, and cinnamon until well blended.
In a large bowl using an electric mixer, beat the softened butter and sugar on medium-high speed for 3-4 minutes until light and fluffy.
Add the eggs one at a time, beating well after each addition. Add vanilla and almond extracts if using.
Mix in the lemon zest and fresh lemon juice until just combined.
With the mixer on low speed, add about one-third of the dry ingredients to the butter mixture, then half the milk. Continue alternating, ending with the dry ingredients.
Gently fold in the poppy seeds until evenly distributed.
Pour the batter into the prepared bundt pan and spread evenly. Tap the pan gently on the counter a few times to release air bubbles.
Bake for 35-40 minutes, or until a toothpick inserted into the center comes out clean.
Let the cake cool in the pan for exactly 10 minutes, then invert onto a cooling rack to cool completely.
While the cake cools, make the glaze by whisking together the powdered sugar, lemon juice, and cinnamon until smooth.
When the cake is completely cool, drizzle the glaze over the top, letting it flow down the sides.
Immediately sprinkle with additional poppy seeds, lemon zest, or sliced almonds if desired before the glaze sets.
Notes
For maximum lemon flavor, use fresh lemons for both juice and zest rather than bottled juice.
Make sure all ingredients are at room temperature before beginning for the best texture.
The cake can be made a day ahead; the flavors actually develop and improve overnight.
Nutrition facts are estimates and may vary based on ingredients used, portion sizes, and preparation methods.