Heat the oven to 350°F (175°C). Grease and line a 9-by-13-inch pan.
Whisk flour, baking powder, and salt. Beat the egg yolks with half the sugar until pale, then beat in the milk and vanilla.
Beat the egg whites to soft peaks, gradually add the remaining sugar, and beat to firm peaks. Fold the yolk mixture and dry ingredients into the whites in alternating additions.
Spread into the pan and bake for 30 to 35 minutes, until lightly golden and set.
Soak and Chill:
Cool the cake for 10 minutes. Poke holes all over with a skewer.
Whisk the evaporated milk, condensed milk, and cream together. Pour slowly over the cake, allowing it to absorb between additions.
Cover and refrigerate for at least 4 hours.
Top and Serve:
Whip the cold cream with the powdered sugar until soft peaks form. Spread over the chilled cake.
Dust with cinnamon, add strawberries, and cut into squares to serve.
Notes
Pour the milk mixture slowly, especially around the edges, so the cake absorbs it evenly.
For a coffee variation, stir one tablespoon of instant espresso into the milk soak.