Hello

I to used to go to 37th Street School back in the '70s, and I too loved that coffee cake. The Los Angeles Times actually published a recipe a couple years back in their food section after someone asked us a similar question as yours. I didn't write down but I found a copy of it. Here is below, and hope you enjoyed it.

Old Fashioned Coffee Cake
Source: Los Angeles Unified School District Food Services Branch

BATTER:
3 3/4 cups all purpose flour
1/2 cup plus 2 tbsp. non-fat dry milk
1 1/4 tsp. salt
1 tsp. nutmeg
1 1/2 tsp. cinnamon
3 1/2 tsp. baking powder
3/4 tsp. baking soda
2 tbsp. vinegar
1 1/2 cups water
1 cup plus 2 tbsp. salad oil
1 1/4 cups brown sugar, packed
1 cup granulated sugar
2 eggs

TOPPING:
3/4 cup plus 3 tbsp. all purpose flour
1/4 cup plus 1 tbsp. brown sugar, packed
1/4 cup granulated sugar
dash salt
1/4 tsp plus 1/8 tsp. cinnamon
1/4 tsp plus 1/8 tsp. nutmeg
1/4 cup vegetable oil

BATTER:
In a bowl, combine flour, dry milk, salt, nutmeg, cinnamon, baking powder and baking soda. Set Aside. Combine vinegar and water in a measuring cup. Set Aside.

In mixer bowl, blend together the oil, brown sugar and granulated sugar on low speed for 1 minute. Add eggs and continue to blend on low speed for 1 minute. While mixer is on low speed, add the dry ingredients alternately with the water and vinegar to oil-sugar mixture. Scrape down bowl, then blend on medium speed for 1 additional minute. Evenly divide batter between two greased 9x9-inch pans. Sprinkle 3/4 cup topping evenly over batter in each pan.

Bake until tooth pick comes out clean when inserted in the center of cake.
Conventional Oven: 375F for 45-55 minutes.
Convection Oven: 325 F for 35-40 minutes.

TOPPING:
In mixer bowl, combine all ingredients except oil. Blend on low Speed for 1 minute. Add oil gradually and continue to blend until topping is crumbly.

PORTIONS: 18, SIZE: Cut 9 per Pan, PANS: 2 (9x9-inch)