• Grease bundt cake pan with non- stick cooking spray. Preheat oven to 325 degrees F/162 degrees C.

Make butter tart swirl filling:

• In a medium pot on stove top, add 1 teaspoon vanilla to ¼ cup and 2 Tblsp whipping cream, heat to medium low,  then add 2 Tblsp and 2 teaspoon butter.
• In a separate large bowl, combine 3 eggs, and 1 ½ cups brown sugar.
• Add egg mixture to warm cream mixture and simmer on low, then add 1 ½ teaspoon vinegar and whisk in 2 teaspoon of cornstarch.
• Add ½ cup raisins or chopped pecans.
• Keep whisking until thickened on med/ low heat for about 12 -15 minutes. Be patient and keep whisking, as it won't really start to thicken until the last 5-7 minutes.

  It should be the consistency of thick gravy after 15 minutes. If it's not, then you need to add more cornstarch and keep whisking.
• Remove from heat and cool. Once it's cooled, it will be very thick like pudding.

  *If it is not this thick it won't work - the cake won't cook properly!

  *This is why I often make it the night before so it has time to cool and sit in the fridge and thicken.

  **To thicken it quickly, put it in the freezer for 30 minutes.

Make Cake:

• Pour 1 teaspoon vinegar into 1 cup milk (let stand ).
• Mix 2 ½ cups flour and ½ teaspoon baking powder together – set aside.
• Cream 1 cup unsalted butter and 2 cups brown sugar with electric hand mixer, (or with a paddle attachment in the bowl of a stand mixer) then beat in 1 teaspoon each butter and vanilla extracts, 2 eggs and ¼ cup whipping cream.
• Mix dry ingredients into wet and stir until combined. Mix 1 teaspoon baking soda into milk mixed with vinegar, stir and allow a moment for it to bubble up.
• Then fold into cake mix and stir until just combined.
• Pour ½ the cake batter into the bundt cake pan. Drop spoonfuls of  the butter tart swirl filling (about ½ of the filling) over cake and swirl gently with a knife. 
• Pour in remaining batter and swirl in the remaining butter tart swirl filling, using the same technique.
• Bake in preheated oven for approximately 1 hour or until cake tester/toothpick  comes out clean.
• If it's not done, cover will foil so it won't darken anymore and put it back in the oven, check it at 5 minute intervals.
• Allow it to cool in pan on trivet for at least 10 minutes.
• Remove from pan and cool for another 20 minutes on wire rack.

Glaze:

• Brown butter: Melt ¼ cup unsalted butter in a small saucepan over medium heat and continue to cook until butter turns a light golden brown and is fragrant (caramel odor). SEE VIDEO IN RECIPE NOTES
• Remove from heat and add 1 teaspoon maple extract (be careful because it will bubble up and can spray). Then cool to room temperature. Whisk the butter mixture with 1 cup confectioners sugar and add 3 Tblsp of whipping cream. 
• Pour Brown butter maple glaze over cake and allow to harden a few minutes.