Preheat oven to 350°F. Line 9x13-inch baking dish with parchment paper and set aside.
In medium sauce pan, add raspberries, sweetened condensed milk, and cornstarch. Cook over medium heat until mixture comes to a simmer. Stir very gently, 2 to 3 minutes; remove from heat and set aside.
In large bowl, add butter and sugar. Beat on medium speed until light and creamy, scraping down sides of bowl, as needed. Add vanilla extract, lemon zest, lemon extract, and salt. Beat to combine. Add flour and beat until JUST combined. Do not over-mix.
Press a little over half of dough into bottom of prepared baking dish. Pour raspberry mixture over top and smooth, using a spatula, into one even layer. Drop small pieces of remaining dough over raspberry mixture. (The "dough" is very thick and sticky -- don't add more flour).
Bake 28-32 minutes, until top is golden. Remove from oven and let bars cool to room temperature before cutting. Bars are best enjoyed within 1-2 days.