Preheat oven to 350ºF, and line a muffin pan with cupcake liners.
In a large mixing bowl, whisk together the flour, baking soda, salt, and sugar until well blended. Add the milk, sour cream, oil, jam, egg, vanilla, and almond extract and stir until just combined.
Pour batter into cupcake liners, filling 2/3 of the way. Bake in the oven for 16-18 minutes, or until a toothpick inserted in the center comes out clean. Allow cupcakes to cool in the pan for 5 minutes before transferring to a wire rack to cool completely.
Make the Buttercream:
In a heat-safe bowl, whisk the egg whites, sugar, and salt together. Remove bowl from mixer, then place over a pan of simmering water, not touching the water. Whisk until warm and sugar is dissolved, about 2-3 minutes. Mixture should feel completely smooth with no graininess when a bit is rubbed between two fingers. Remove from heat and chill in the freezer for 15-20 minutes, or until mixture is cool.
Meanwhile, in the bowl of a stand mixer fitted with the paddle attachment, beat the butter on high until fluffy and lightened in color. Add about half of the cooled syrup and beat for one minute. Add the last half and continue beating until mixture is thick, yet fluffy. With the mixer on low, add the lemon juice, vanilla, and almond extract, and beat until smooth and fully incorporated.
Frost or pipe buttercream onto cooled cupcakes, as desired. Top each cupcake with a fresh strawberry.
Notes
*If frosting appears curdled or runny after combining the butter and cooled syrup, remove bowl from the mixer and chill in the refrigerator for 15-20 minutes. Return bowl to the mixer, and beat on high until mixture has come together. *Cupcakes frosted with Swiss meringue buttercream may be covered and stored on the counter at room temperature for a 2 days. If storing in the refrigerator, remove cupcakes from the refrigerator 30 minutes before serving to bring back to room temperature.